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').

Q: Millipedes have ____ pairs of legs on each body segment.\Question: Choose the right answer from options given a) seven b) ten c) six d) two

A: d
****
Q: Most endocrinologists see patients every ____ months throughout the pregnancy.\Question: Choose the right answer from options given a) six b) two c) zero d) three

A: b
****
Q: Gorillas are sexually mature at ____ to nine years of age.\Question: Choose the right answer from options given a) ten b) six c) eight d) five

A:
b
****