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: Respiratory therapists complete ____ to four years of education.\Question: Choose the right answer from options given a) one b) nine c) zero d) two
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: Toddlers are approximately ten inches tall and babies are ____ inches tall.\Question: Choose the right answer from options given a) ten b) eight c) no d) seven
Example Output:
b