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: Human feet bear average five to ____ hundreds tons of weight everyday.\Question: Choose the right answer from options given a) six b) eight c) five d) nine
Example Output: a

Example Input: Brain death occurs in just four to ____ minutes unless the heart rhythm is restored.\Question: Choose the right answer from options given a) ten b) three c) six d) nine
Example Output: c

Example Input: Trefoil is an indeterminate bloomer and flowers continuously for nearly ____ weeks.\Question: Choose the right answer from options given a) zero b) six c) five d) seven
Example Output:
d