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:
Stable oxygen has eight protons and ____ neutrons.\Question: Choose the right answer from options given a) eight b) ten c) three d) zero

Ex Output:
a


Ex Input:
Banks hold ____ excess reserves and the public holds no currency.\Question: Choose the right answer from options given a) two b) seven c) ten d) no

Ex Output:
d


Ex Input:
Studies show that childhood obesity is epidemic and that ____ in five children is overweight.\Question: Choose the right answer from options given a) one b) two c) nine d) ten

Ex Output:

a