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: Nymphs feed and mature through ____ instars in about six to eight weeks.\Question: Choose the right answer from options given a) four b) eight c) five d) no
Example Output: c

Example Input: Females can only have four babies at ____ time.\Question: Choose the right answer from options given a) no b) one c) nine d) three
Example Output: b

Example Input: Clamps exist constantly on all septa, ____ polifications of clamps.\Question: Choose the right answer from options given a) no b) seven c) nine d) zero
Example Output:
a