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: Carbon can bond to a maximum of ____ atoms.\Question: Choose the right answer from options given a) six b) ten c) five d) four
Example Output: d

Example Input: Nymphs emerge in ____ to seven days and flatten themselves against the leaf to feed.\Question: Choose the right answer from options given a) one b) five c) nine d) two
Example Output: b

Example Input: Babies crawl into a pouch on the mother's belly and stay there ____ months.\Question: Choose the right answer from options given a) four b) five c) no d) nine
Example Output:
a