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: Many comets have ____ tails.\Question: Choose the right answer from options given a) two b) six c) three d) one
Example Output: a

Example Input: Women gain ____ years per child they had.\Question: Choose the right answer from options given a) ten b) nine c) four d) two
Example Output: d

Example Input: Some individuals remain with their parents for as long as ____ months after fledging.\Question: Choose the right answer from options given a) six b) ten c) four d) seven
Example Output:
a