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: Perennial grass takes ____ to five years before it is mature enough to produce adequate seed.\Question: Choose the right answer from options given a) six b) zero c) three d) no
Example Output: c

Example Input: Every person is a carrier for about ____ rare genetic conditions.\Question: Choose the right answer from options given a) nine b) ten c) six d) three
Example Output: b

Example Input: Young worms mature in the large intestine in three to ____ months, then begin the cycle anew.\Question: Choose the right answer from options given a) no b) eight c) zero d) four
Example Output:
d