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: 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: Healthcare providers diagnose ____ general types of insomnia.\Question: Choose the right answer from options given a) two b) eight c) one d) three
Example Output: a

Example Input: Charged batteries give ____ hours of light with full charge.\Question: Choose the right answer from options given a) two b) four c) three d) five
Example Output:
a