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:
Perennial grass takes three to ____ years before it is mature enough to produce adequate seed.\Question: Choose the right answer from options given a) five b) seven c) six d) four

Ex Output:
a


Ex Input:
Many animals use two or ____ forest structure types.\Question: Choose the right answer from options given a) eight b) zero c) two d) three

Ex Output:
d


Ex Input:
Bluebirds often have ____ broods in a season.\Question: Choose the right answer from options given a) six b) three c) five d) two

Ex Output:

d