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: Reptiles also have scaly skin and a ____ chambered heart.\Question: Choose the right answer from options given a) zero b) one c) ten d) three

A: d
****
Q: Slack tides occur three or ____ times.\Question: Choose the right answer from options given a) zero b) one c) four d) ten

A:
c
****