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').

Ex Input:
Cows can be up to ____ times more active than normal while in heat.\Question: Choose the right answer from options given a) eight b) nine c) two d) six

Ex Output:
a

Ex Input:
Bacteria come in ____ basic shapes.\Question: Choose the right answer from options given a) five b) one c) three d) nine

Ex Output:
c

Ex Input:
Twins are a genuine rarity, and only a few births of ____ or more foals have ever been recorded.\Question: Choose the right answer from options given a) one b) seven c) three d) no

Ex Output:
c