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:
All quetzals have ____ legs.\Question: Choose the right answer from options given a) four b) zero c) eight d) ten

Ex Output:
a


Ex Input:
Many scientists believe the neutrino has ____ mass at all.\Question: Choose the right answer from options given a) eight b) zero c) two d) no

Ex Output:
d


Ex Input:
Coffee trees reach maturity between ____ and four years when their clusters of fruit turn deep red.\Question: Choose the right answer from options given a) no b) three c) nine d) five

Ex Output:

b