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:
Some sources claim there are more like ____ million vertebrate animals in zoos.\Question: Choose the right answer from options given a) six b) five c) one d) three

Ex Output:
b


Ex Input:
Many people have ____ symptoms until they suffer chest pains or a heart attack.\Question: Choose the right answer from options given a) three b) one c) no d) seven

Ex Output:
c


Ex Input:
Some sharks disappear from feeds for periods of around ____ months.\Question: Choose the right answer from options given a) three b) nine c) ten d) seven

Ex Output:

a