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]: 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]: Tetrapods are animals that have ____ legs or leg-like appendages.\Question: Choose the right answer from options given a) four b) one c) ten d) six
[A]: a


[Q]: Autism is present at birth and the characteristics become evident in the first ____ years.\Question: Choose the right answer from options given a) ten b) three c) eight d) four
[A]:
b