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:
Nightmares happen frequently in childhood, especially between the ages of ____ and six.\Question: Choose the right answer from options given a) three b) eight c) no d) ten

Ex Output:
a


Ex Input:
Some European countries require ____ years of education.\Question: Choose the right answer from options given a) no b) nine c) six d) three

Ex Output:
d


Ex Input:
Horses gain twelve additional permanent molars from one to ____ and a half years of age.\Question: Choose the right answer from options given a) two b) three c) five d) one

Ex Output:

b