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: Cats have ____ sets of vocal cords.\Question: Choose the right answer from options given a) zero b) nine c) two d) three
Example Output: c

Example Input: Women live an average of five to ____ years longer then men.\Question: Choose the right answer from options given a) one b) five c) ten d) seven
Example Output: d

Example Input: Air quality is important to long-term economic growth for ____ reasons.\Question: Choose the right answer from options given a) three b) five c) no d) four
Example Output:
a