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').

Example Input: Piglets normally grow about half their potential growth rate from birth to ____ weeks of age.\Question: Choose the right answer from options given a) zero b) no c) five d) three
Example Output: d

Example Input: Ossification begins up to ____ months before birth.\Question: Choose the right answer from options given a) nine b) seven c) three d) six
Example Output: b

Example Input: Chronic insomnia occurs on most nights for at least ____ weeks.\Question: Choose the right answer from options given a) four b) nine c) no d) three
Example Output:
d