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:
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:
Insects have ____ pairs of legs and three body segments.\Question: Choose the right answer from options given a) one b) nine c) no d) three

Ex Output:
d


Ex Input:
Air is over ____ times more dense than helium.\Question: Choose the right answer from options given a) two b) ten c) seven d) three

Ex Output:

c