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: Ozone is a molecule containing ____ oxygen atoms.\Question: Choose the right answer from options given a) one b) nine c) no d) three
Example Output: d

Example Input: Females can only have four babies at ____ time.\Question: Choose the right answer from options given a) no b) one c) nine d) three
Example Output: b

Example Input: Shigellosis is extremely rare below the age of ____ months.\Question: Choose the right answer from options given a) ten b) two c) zero d) six
Example Output:
d