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: Illiteracy is ____ percent higher among women than men.\Question: Choose the right answer from options given a) seven b) six c) zero d) five
Example Output: a

Example Input: Most people recover in one to ____ months.\Question: Choose the right answer from options given a) no b) three c) seven d) eight
Example Output: b

Example Input: Irrigation can increase land productivity by ____ to seven times, especially in the north.\Question: Choose the right answer from options given a) six b) eight c) nine d) three
Example Output:
d