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').

Input: Consider Input: Acoustic guitars come in ____ types.\Question: Choose the right answer from options given a) two b) ten c) one d) four

Output: a

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

Output: b

Input: Consider Input: Birds can nest in snags as small as ____ inches in diameter.\Question: Choose the right answer from options given a) four b) six c) three d) two
Output: a