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:
Most children have a vocabulary of eight to ____ words, including names, by eighteen months of age.\Question: Choose the right answer from options given a) ten b) one c) seven d) eight

Ex Output:
a


Ex Input:
Hydra has ____ distinct methods of reproduction, asexual and sexual.\Question: Choose the right answer from options given a) two b) zero c) no d) ten

Ex Output:
a


Ex Input:
Some children walk when they are ____ months old.\Question: Choose the right answer from options given a) no b) two c) seven d) three

Ex Output:

c