Given a sentence with a missing word, pick the answer option that best fills out the missing word in the sentence. Indicate each answer with its index ('a', 'b', 'c', 'd').

Alleles fall into ____ classes based on somatic, gonadal and dauer phenotypes.\Question: Choose the right answer from options given a) ten b) six c) eight d) no
b

Western culture offers only ____ genders, man or woman.\Question: Choose the right answer from options given a) three b) two c) one d) four
b

Humans host ____ species of louse, the head louse , the body louse and the pubic louse .\Question: Choose the right answer from options given a) no b) three c) two d) six

b