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:
Electrons have almost ____ mass and are negatively charged.\Question: Choose the right answer from options given a) three b) seven c) zero d) no

Ex Output:
d


Ex Input:
Vision problems affect one in ____ school-aged children.\Question: Choose the right answer from options given a) six b) four c) seven d) one

Ex Output:
b


Ex Input:
Ozone is a molecule made of ____ oxygen atoms.\Question: Choose the right answer from options given a) ten b) no c) three d) one

Ex Output:

c