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 have four stomachs, and the first ____ yield merchantable tripe.\Question: Choose the right answer from options given a) two b) five c) zero d) three

Ex Output:
d


Ex Input:
Pelicans use ____ different ways to feed.\Question: Choose the right answer from options given a) no b) nine c) one d) two

Ex Output:
d


Ex Input:
All species have ____ basic requirements for survival.\Question: Choose the right answer from options given a) two b) one c) four d) no

Ex Output:

c