1. Each of the following statements concerning the surface structures of bacteria
is correct EXCEPT:
A. Pili mediate the interaction of bacteria with mucosal epithelium
B. Polysaccharide capsules retard phagocytosis
C. Both gram-negative rods and cocci have lipopolysaccharide ("endotoxin") in their cell wall
D. Bacterial flagella are nonantigenic in humans because they closely resemble human flagella
in chemical composition
2. Each of the following statements concerning bacterial spores is correct EXCEPT:
A. Their survival ability is based on their enhanced metabolic activity
B. They are formed by gram-positive rods
C. They can be killed by being heated to 121 °C for 15 minutes
D. They contain much less water than bacterial cells
3. Each of the following statements regarding the selective action of antibiotics on bacteria is
correct EXCEPT:
A. Chloramphenicol affects the large subunit of the bacterial ribosome, which is different from
the large subunit of the human ribosome
B. Isoniazid affects the DNA polymerase of bacteria but not that of human cells
C. Sulfonamides affect folic acid synthesis in bacteria, a pathway that does not occur in
human cells
D. Penicillins affect bacteria rather than human cells because bacteria have a cell wall,
whereas human cells do not
4. Each of the following statements concerning the normal flora is correct EXCEPT:
A. The most common organism found on the skin is Staphylococcus epidermidis
B. Escherichia coli is a prominent member of the normal flora of the throat
C. The major site where Bacteroides fragilis is found is the colon
D. One of the most common sites where Sktphylococciis aureus is found is the nose
5. Each of the following statements concerning the resistance of bacteria to antimicrobial drugs
is correct EXCEPT:
A. Resistance to chloramphenicol is known to be due to an enzyme that acetylates the drug
B. Resistance to penicillin is known to be due to reduced affinity of transpeptidases
C. Resistance to penicillin is known to be due to cleavage by β-iactamase
D. Resistance to tetracycline is known to be due to an enzyme that hydrolyzes the ester linkage
6. Each of the following statements concerning the mechanism of action of antibacterial drugs
is correct EXCEPT:
A. Cephalosporins are bactericidal drugs that inhibit the transpeptidase reaction
and prevent cell wall synthesis
B. Tetracyclines are bacteriostatic drugs that inhibit protein synthesis by blocking tRNA binding
C. Aminoglycosides are bacteriostatic drugs that inhibit protein synthesis by activating
ribonuclease, which degrades mRNA
D. Erythromycin is a bacteriostatic drug that inhibits protein synthesis by blocking translocation of the
polypeptide
7. Each of the following statements concerning the Gram stain is correct EXCEPT:
A. Escherichia coli stains pink because it has a thin peptidoglycan layer
B. Streptococcus pyogenes stains blue be cause it has a thick peptidoglycan layer
C. Mycobacterium tuberculosis stains blue because it has a thick lipid layer
D. Mycoplasma pncumoniae isn't visible in the Gram stain because it doesn't have a cell wall
8. In the Gram stain, the decolorization of cramnegative bacteria by alcohol is MOST closely related to
A. proteins encoded by F plasmids .
B. lipids in the cell wall
C. 70S ribosomcs
D. branched polysaccharicies in the capsule
9. Each of the following statements concerning resistance to antibiotics is correct EXCEPT:
A. Resistance to aminoglycosides can be due to phosphorylating enzymes encoded by R plasmids
B. Resistance to sulfonamides can be due to enzymes that hydrolyze the five-membered ring structure
C. istance to penicillins can be due to alterations in binding proteins in the cell membrane
D. Resistance to cephalosporins can be due to leavage of the β-lactam ring
10. Each of the following statements concerning penicillin is correct EXCEPT:
A. An intact (3-lactam ring of penicillin is required for its activity
B. The structure of penicillin resembled that of a dipeptide of alanine, which is a component of
peptidoglycan
C. Penicillin is a bacteriostatic drug because autolytic enzymes are not activated
D. Penicillin inhibits transpcptiduses, which are required for cross-linking peptidoglycan
11. Each of the following statements concerning the killing of bacteria is correct EXCEPT:
A. A 70% solution of ethanol kills more effectively than absolute (100%) ethanol
B. An autoclave uses steam undef pressure to reach the killing temperature of 121 °C
C. The pasteurization of milk kills pathogens but allows many organisms and spores to survive
D. Iodine kills by causing the formation of thymine dimers in bacterial DNA
12. Each of the following statements concerning the normal flora is correct EXCEPT:
A. The normal flora of the colon consists predominantly of anaerobic bacteria
B. The presence of the normal flora prevents certain pathogens from colonizing the upper
respiratory tract
C. Fungi, eg, yeasts, are not members of the normal flora
D. Organisms of the normal flora are permanent residents of the body surfaces
13. Each of the following statements concerning the normal flora is correct EXCEPT:
A. Streptococcus mutans is found in the mouth and contributes to the formation of dental caries
B. The predominant organisms in the alveoli are viridans streptococci
C. Bacteroides fragilis is found in greater numbers than Escherichia coli in the colon
D. Candida albicans is part of the normal flora of both men and women
14. Each of the following statements concerning peptidoglycan is correct EXCEPT:
A. It has a backbone composed of alternating units of muramic acid and acetylglucosamine
B. Cross-links between the tetrapeptides involve D-alanine
C. It is thinner in gram-positive than in gramnegative cells
D. It can be degraded by lysozyme
15. Which one of the statements is the MOST accurate comparison of human, bacterial,
and fungal cells
A. Human cells undergo mitosis, whereas neither bacteria nor fungi do
B. Human and fungal cells have a similar cell all, in contrast to bacteria, whose cell
wall contains peptidoglycan
C. Human and bacterial cells have plasmids, hereas fungal cells do not
D. Human and fungal cells have similar ribosomes, whereas bacterial ribosomes are different
16. Each of the following events involves recombination of DNA EXCEPT:
A. transduction of a chromosomal gene
B. transposition of a mobile genetic element
C. integration of a temperate bacteriophage
D. conjugation, eg, transfer of an R (resistance) factor
17. Each of the following statements concerning the mechanism of action of antimicrobial drugs
is correct EXCEPT:
A. Vancomycin acts by inhibiting peptidoglycan synthesis
B. Quinolones, such as ciprofloxacin, act by inhibiting the DNA gyrase of bacteria
C. Erythromycin is a bactericidal drug that disrupts cell membranes by a detergentlike action
D. Aminoglycosides such as streptomycin are bactericidal drugs that inhibit protein synthesis
18. Which of the following events is MOST likely to.be due to bacterial conjugation?
A. A strain of Corynebacterium diphtheriae produces a toxin encoded by a prophage
B. A strain of Pseudomonas aeruginosa produces β-lactamase encoded by a piasmid
similar to a piasmid of another gram-negative organism
C. An encapsulated strain of Streptococcus pneumonia acquires the gene for capsule
formation from an extract of DNA from another encapsulated strain
D. A gene encoding resistance to gentamicin in the Escherichia coli chromosome
appears in the genome of a virulent bacteriophage that has. infected E coli
19. Each of the following statements concerning bacterial spores is correct EXCEPT:
A. Spores arc formed under adverse environmental conditions such as the absence of a
carbon source
B. Spores are resistant to boiling
C. Spores are metabolically inactive and contain dipicolinic acid, a calcium chelator
D. Spores are formed primarily by organisms of the genus Neisseria
20. Each of the following is a typical property of obligate anaerobes EXCEPT:
A. They generate energy by using the cytochrorne svstem
B. They grow best in the absence of air
C. They lack superoxide dismutase
D. They lack catalase
21. Each of the following statements concerning the killing of bacteria is correct EXCEPT:
A. Lysozyme in tears can hydrolyze bacterial cell walls
B. Silver nitrate can inactivate bacterial enzymes
C. Detergents can disrupt bacterial eel I membranes
D. Ultraviolet light can degrade bacterial capsules
22. Chemical modification of benzylpenicillin (penicillin G) has resulted in several beneficial
changes in the clinical use of this drug. Which one of the following is NOT one of those
beneficial changes?
A. Lowered frequency of anaphylaxis
B. Increased activity against gram-negative rods
C. Increased resistance to stomach acid
D. Reduced cleavage by penicillinase
23. Each of the following statements concerning bacterial and human cells is correct EXCEPT:
A. Bacteria are prokaryotic (ie, they have one molecule of DNA, are haploid, and have
no nuclear membrane), whereas human cells are eukaryotic (ie, they have multiple
chromosomes, are diploid, and have a nuclear membrane)
B. Bacteria derive their energy by oxidative phosphorylation within mitochondria in a
manner similar to human cells
C. Bacterial and human ribosomes are of different sizes and chemical compositions
D. Bacterial cells possess peptidoglycan, whereas human cells do not
24. Each of the following statements concerning the mechanisms of resistance to antimicrobial
drugs is correct EXCEPT:
A. R factors are plasmids that carry the genes for enzymes which modify one or more drugs
B. Resistance to some drugs is due to a chromosomal mutation that alters the receptor
for the drug
C. Resistance to some drugs is due to transposon genes that code for enzymes which in
activate the drugs
D. Resistance genes are rarely transferred by conjugation
25. Each of the following statements concerning penicillin is correct EXCEPT
A. The drug is bacteriostatic
B. The drug inhibits cell wall synthesis
C. The drug is made by a fungus
D. The drug may destroy bacteria by activating their own autolysins
26. Each of the following statements concerning the structure and chemical composition of
bacteria is correct EXCEPT:
A. Some gram-positive cocci contain a layer of teichoic acid external to the peptidoglycan
B. Some gram-positive rods contain dipicolinic acid in their spores
C. Some gram-negative rods contain lipid A in their cell wall
D. Some mycoplasmas contain pentaglycine in their peptidoglycan
27. What is disbacteriosis?
A. Reduction of quantity of the anaerobic bacteria of the colon.
B. Infringements of balance between microbes of the small intestine and the colon.
C. Quantitative and qualitative infringements of balance between microbic populations in structure of
microflora
D. Increases of quantityof pathogenic microorganisms at surfaces of a skin
E. Condition of microflora of the experimental animal, caused by intervention of the experimenter
28. Choose drugs which are used for treatment dysbacteriosis:
A. Penicillinum, Cephalosporinum
B. Antimicrobic serums and immunoglobulines
C. Vitamins and hormones
D. Lysozym and interferon
E. Colibacterin, bifidobacterin
29. For the first - second degrees of cleanliness of vaginal secret typically:
A. The alkaline pH, is not enough glicogen and glucose
B. The pH is 4.7, presence of lactic acid bacilli
C. The alkalescent pH, leukocytes, staphylococci
D. The alkaline pH, staphylo-and streptococci, leukocytes
E. The alkaline pH, presence of proteins, single cocci
30. Anaerobic conditions can be created with the help:
A. Zoessler's method
B. Shukevich's method
C. Veinberg's method
D. Fortnes' method
E. Paster' method
31. Choose the nutrients media on which it is possible to grow anaerobic microorganisms:
A. Endo's and Lewin's media
B. Meat - pepton agar, meat - pepton broth
C. Sugar - blood agar Zoessler, Kitt-Tarozzi's medium
D. The curtailed serum, meat- pepton gelatin
E. Blood agar, serum agar
32. At definition peptolytic properties determine allocation in the nutrient medium:
A. Carbonic acids and waters
B. Glucose and lactoses
C. Carbonic acids and nitrogen
D. Mannitol and metanol
E. Indol and hydrogen sulphide
33. At allocation of pure culture of anaerobic microorganisms the received isolated colony sow on:
A. Kitt-Tarozzi's medium
B. Hiss media
C. Zoessler's medium
D. Endo's medium
E. Ploskirev medium
34. The third stage of allocation of pure culture of aerobic microorganisms will be:
A. Inoculating of a mix (material) on a solid nutrient medium
B. Biochemical and serological identification
C. Microscopic examination of a material
D. Check of cleanliness of the allocated culture and its identification
E. Studying of isolated colonies and Inoculating on the slant agar
35. Resistance of bacteria to acid depends from present in cytoplasm
А. lipopolysaccharides
В. oxyacid, fatty acid
С. acetylglucosamine
D. diaminopimelic acid
Е. poliphosphates
36. Cell wall of gram-positive bacteria consist of:
А. thin monolayer peptidiglycan
В. lipoproteins
С. polilayer peptidiglican
D. lipopolysaccharides
Е. outer membrane
37. Which with these substances can damage bacteria cell wall :
А. sulphonamides
В. lysozyme
С. interferone
D. alcohol
Е. streptomycin
38. After what sign of mycoplasma differ from bacteria :
А. by structure of the nucleosis
В. by absence of cell wall
С.by intracellular parasite
D. by tinctorial properties
Е. by structure of cytoplasmatic membrane
39. Which concentration of ethyl alcohol would is the most effective disinfectant?
A. 100%
D. 50%
B. 70%
E. 30%
C. 60%
40. Gnotobiology is a science which studies:
A. Microflora of the person
B. Microflora of experimental animals
C. Life of the microbe-free animals
D. Microflora of different parts of an organism
E. Influence of various factors on normal microflora
41. Choose among given microorganisms which occupy a skin:
A. Bacteroides, Vibrio, Spirillum
B. Bacillus subtilis, Streptococcus pneumoniae, Pseudomonades
C. Clostridium, Staphylococcus aureus, Micrococcus roseus,
D. Staphylococcus, Propionobacterium, Peptococcus
E. Escherichia coli, Clostridium perfringens, Neisseria
42. Choose among the listed drugs eubiotycs:
A. Bacteriocines
B. Antibiotics
C. Bificol
D. Lysozim
E. interferon
43. Choose among the microorganisms of a colon given the basic kinds:
A. Bacteroides, Bifidobacterium, Lactobacillus
B. Staphylococci, streptococci, Proteus
C. Clostridium, peptococci, esherichia
D. Candida, spirochetes, micrococci
E. Diphtheroides, spirillum, fungi
44. For an establishment of a kind of the allocated pure culture of bacteria
serological identification has crucial importance.
What is serological identification? Choose the true answer.
A. Establishment of a kind of bacteria on biochemical properties
B. Definition of ability to decompose the curtailed serum
C. Definition of antigenic structure of bacteria
D. Establishment of a kind of bacteria on ability to reduce the certain dyes
E. Definition of genic structure of bacteria's nucleoid
45. Choose among listed nutrients media on which study peptolytic properties of bacteria:
A. Meat - pepton agar
B. Sugar agar
C. The curtailed serum
D. Meat - pepton broth
E. Gelatin
46. It is possible to allocate anaerobic microorganisms on a method:
A. Fortner's
B. Veinberg's
C. Shukevich's
D. Paster's
E. Loeffler's
47. Choose among the listed microorganisms obligate aerobes.
A. Neisseria gonorrhoeae, Streptococcus pneumoniae
B. Clostridium tetani, Clostridium botulini
C. Shigella dysenteriae, Salmonella typhi
D. Bacillus anthracis, Brucella melitensis
E. Mycobacterium tuberculosis, Micrococcacae
48. The second stage of allocation of pure culture of aerobes will be:
A. Inoculating of a mix (material) on a solid nutrient medium
B. Check of cleanliness of the allocated culture and its identification
C. Biochemical and serological identification
D. Studying of isolated colonies and Inoculating on the slant agar
E. Microscopic examination of a material
49. Upon staining spores by Auesko’s method after treating
with hydrochloric acid and heating the preparation:
А. is staining with mеthylene blue
В. is washing with water and drying out
С. is staining with Ziehl’s phenol fuchsine
D. is treating with sulphuric acid
Е. is staining with crystal violet
50. Upon staining by Ziehl-Neelsen’s method after treating with
sulphuric acid the preparation is necessary ussing
А. Ziehl’s phenol fuchsine
В. Alcohol
С. Меthylene blue
D. Washing with water
Е. iodine solution
51. Spores are necessary to bacteria for:
А. Survival into human and animal’s organism
В. Reproduction
С. Survival in an external environment
D. Defence from fagocytosis
Е. Defence from acid in stomack
52. Pneumonic plague can be transmitted from man to man by:
A. droplet infection.
B. inoculation.
C. ingestion.
D. all of the above routes.
53. Route/s of infection in Legionnaires' disease is/are:
A. respiratory tract.
B. gastrointestinal tract.
C. skin.
D. all of the above.
54. Which of the following determine/s the virulence
of Haemophilus Influenzae?
A. Capsular polysaccharide.
B. Pili.
C. Outer membrane proteins.
D. All of the above.
55. The most infective stage in whooping cough is:
A. catarrhal stage.
B. paroxysmal stage.
C. convalescent stage.
D. when the patient develops complications.
56. Brucellae are transmitted to humans by:
A. direct contact with animal tissues.
B. ingestion of contaminated meat.
C. ingestion of raw infected milk.
D. all of the above.
57. Which of the following Brucella spp. is/are capnophilic?
A. B. abortus.
B. melitensis.
C. suis.
D. All of the above.
58. Earliest growth of diphtheria bacilli can be detected on:
A. blood agar.
B. blood tellurite agar.
C. Loeffler's serum slope.
D. nutrient agar.
59. Which of the following sites is most commonly
affected by diphtheria bacilli?
A. Upper respiratory tract.
B. Skin.
C. Cornea.
D. Conjunctiva.
60. Malignant pustule is characteristic of:
A. cutaneous anthrax.
B. pulmonary anthrax.
C. intestinal anthrax.
D. all of the above.
61. The causative agent/s of gas gangrene is/are:
A. Clostridium perfringens.
B. novyi.
C. С. septicum.
D. all of the above.
62. Which of the following exotoxins is most toxic?
A. Botulinum toxin.
B. Tetanus toxin.
C. Diphtheria toxin.
D. Cholera toxin.
63.
Antitoxic therapy is useful in:
A. gas gangrene.
B. diphtheria.
C. both of the above.
D. none of the above.
64. Which of the following bacteria is/are sensitive
to thiophen-2-carboxylic acid hydrazide?
A. Mycobacterium tuberculosis.
B. M. bovis.
C. Both of the above.
D. None of the above.
65. BCG vaccine is a:
A. live attenuated preparation.
B. killed preparation.
C. toxoid preparation.
D. recombinant preparation.
66. Leprosy may be acquired by a susceptible person by:
A. skin to skin contact.
B. respiratory tract.
C. both of the above.
D. none of the above.
67. Lactobacilli constitute the normal flora of:
A. adult vagina.
B. prepubertal vagina.
C. post-menopausal vagina.
D. none of the above.
68. Group-specific antigen of Treponema is chemically a:
A. protein.
B. polysaccharide.
C. lipid.
D. nucleic acid.
69. Treponema pallidum cannot be demonstrated by microscopy in:
A. primary syphilis.
B. secondary syphilis.
C. latent syphilis.
D. all of the above.
70. Lyme disease is caused by:
A. Borrelia recurrenlis.
B. dutioni.
C. bnrgdorferi.
D. B. hermsii.
71. The causative agent of epidemic typhus is:
A. Rickettsia prowazekii.
B. R. rickettsii.
C. R. akari.
D. Coxiella burnetii.
72. Which of the following stains can demonstrate Rickettsia
A. Gram stain.
B. Acid-fast stain.
C. Giemsa stain.
D. All of the above.
73. Which of the following tests can aid in the laboratory
diagnosis of clamydial infections?
A. Light microscopy.
B. Immunofluorescence test:
C. ELISA for detection of antigen.
D. All of the above.
74. Cell wall is lacking in:
A. Mycoplasma.
B. Actinomyces.
C. Corynebacterium.
D. Brucella.
75. Which of the following bacteria is negative
for fermentation of mannitol?
A. Shigella dysenteriae.
B. S. Flexneri.
C. S. boydii.
D. S. sonnei.
76. In Widal test, the significant titre for О agglutinins is generally:
A. 1: 50 or more.
B. 1:100 or more.
C. 1:200 or more.
D. 1:400 or more.
77. For determining the serotype of infecting organism, detection
of which agglutinins is more important in Widal test?
A. O.
B. H.
C. Fimbrial.
D. M.
78. For detection of carriers in enteric fever, which
of the following specimens is most important?
A. Faeces,
B. Urine.
C. Blood.
D. Sputum.
79.
80.
Which of the following tests can differentiate between
classical and El Tor biotypes of Vibrio cholerae?
A. Sensitivity to polymyxin B.
B. Agglutination of fowl RBCs.
C. Sensitivity to Mukerjee's group IV phage.
D. All of the above.
Cholera toxin resembles which of the following toxins?
A. Labile toxin of Escherichia coli.
B. Stable toxin of E. coli.
C. Diphtheria toxin.
D. Tetanus toxin.
81. Which of the following species of Bordetella is the most
important human pathogen?
A. B. pertussis.
B. B. parapertussis.
C. В. Bronchiseptica.
D. B. avium.
82.
In which of the following sexually transmitted diseases,
ulcer/s is/are painless?
A. Syphilis.
B. Chancroid.
C. Herpes genitalis.
D. All of the above.
83. A condition in which bacteria circulate in blood
without multiplication is known as:
A. bacteraemia.
B. septicaemia.
C. pyaemia.
D. endotoxaemia.
84. Which of the following viruses cause/s genital infection?
A. Molluscum contagiosum.
B. Human papillomavirus type 6.
C. Herpes simplex virus type 2.
D. All of the above.
85. Which of the following viruses can cause prenatal infection?
A. Rubella.
B. Cytomegalovirus.
C. Varicella-zoster.
D. All of the above.
86. Which of the following vaccines is/are prepared from live microbes
manipulated and attenuated?
A. BCG vaccine.
B. Oral polio vaccine.
C. Measles vaccine.
D. All of the above.
87.
Which of the following molecules would be the best antigens?
A. lipids
B. glucose
C. fatty acids
D. proteins
E. sugars
88. Which part of the antibody molecule reacts with the antigenic
determinants of the antigen?
A. hinge
B. H chains
C. constant sections of the H and L chains
D. L chains
E. variable sections of the H and L chains
89. Which of the following classes of immunoglobulms can cross the placenta?
A. IgG
B. IgM
C. IgA
D. IgD
E. IgE
90. Plasma cells are
A. mature T cells.
B. immature macrophages
C. antibody-producing cells.
D. mature macrophages.
E. immature T cells.
91. A toxoid is a(n)
A. type of antibody that combines with a toxin,
B. type of enzyme that destroys toxins,
C. inactivated toxin.
D.type of bacterium that resists phagocytosis.
E.type of virus.
92. Which category of hypersensitivity BEST de
scribes hemolytic disease of the newborn
caused by Rh incompatibility?
A. Atopic or anaphylactic
B. Cytotoxic
C. Immune complex
D. Delayed
93. AIDS is caused by a human retrovirus that kills
A. B lymphocytes
B lymphocyte stem cells
C. CD4-positive T lymphocytes
D. CDS-ppsitive T lymphocytes
94. The classic complement pathway is initiated by
interaction of Cl with
A. antigen
B. factor B
C. antigen-IgG complexes
D. bacterial lipopolysaccharides
95. Natural killer cells are
A. B cells that can kill without complement
B. cytotoxic T cells
C. increased by immunization
D. able to kill virus-infected cells without
prior sensitization
96. Which one of the following substances is NOT
released by activated helper T cells?
A. Alpha interferon
B. Gamma interferon
C. Interleukin-2
D. Interleukin-4
97. Antigen-presenting cells that activate helper T
cells must express which one of the following
on their surfaces?
A. IgE
B. Gamma intcrferon
C. Class I MHC antigens
D. Class II MHC antigens
98. Complement lyses cells by
A. enzymatic digestion of the cell membrane
B. activation of adenylate cyclase
C. insertion of complement proteins into the
cell membrane
D. inhibition of elongation factor 2
99. Herpes simplex virus type 1 most commonly causes cold sores.
The site of reactivation for this virus is the
A.
B.
C.
D.
E.
vagus nerve
B lymphocyte
epidermal cell
trigeminal nerve
eighth cranial nerve
100. A girl is infected with a paramyxovirus. The cytopathic effect for this virus is
A.
B.
C.
D.
E.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
syncytia formation
major destruction of the tissue culture monolayer
intranuclear inclusion formation
Negri body formation
cellular degranulation
D
A
B
B
D
C
C
B
B
C
D
C
B
C
D
D
C
B
D
A
D
A
B
D
A
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
D
C
E
B
D
C
E
A
D
B
C
B
B
B
C
D
C
A
C
D
B
B
D
C
D
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
C
B
A
D
D
A
B
B
D
C
C
B
A
D
A
D
B
A
D
A
A
D
D
C
A
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
B
B
A
D
A
A
A
A
C
D
D
D
E
A
C
C
B
C
C
D
A
D
C
D
A