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: Chemistry has ____ less important names.\Question: Choose the right answer from options given a) ten b) no c) eight d) nine
Example Output: b

Example Input: Springtails reproduce quickly usually within three to ____ weeks.\Question: Choose the right answer from options given a) five b) six c) nine d) three
Example Output: a

Example Input: Extension is the natural motion opposite to flexion at the ____ starting position.\Question: Choose the right answer from options given a) two b) nine c) zero d) six
Example Output:
c