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: Vision disorders affect one in every ____ school-age children.\Question: Choose the right answer from options given a) five b) four c) nine d) one
Example Output: b

Example Input: Some families have two daddies or ____ mommies.\Question: Choose the right answer from options given a) nine b) seven c) zero d) two
Example Output: d

Example Input: Electric power means ____ gas or oil to spill, and no pollution in the air.\Question: Choose the right answer from options given a) nine b) four c) six d) no
Example Output:
d