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:
Youth unemployment is ____ times the adult level.\Question: Choose the right answer from options given a) one b) three c) seven d) no

Ex Output:
b


Ex Input:
Most children experience at least one episode by the time they are ____ years old.\Question: Choose the right answer from options given a) eight b) one c) ten d) seven

Ex Output:
d


Ex Input:
Most people require a stereoscope to merge the images and perceive ____ dimensions.\Question: Choose the right answer from options given a) five b) ten c) three d) one

Ex Output:

c