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:
Metals often crystallize in a ____ dimensional version of the hexagonal closest packed structure.\Question: Choose the right answer from options given a) one b) seven c) three d) eight

Ex Output:
c


Ex Input:
Potassium helps maintain fluid regulation and normal pH. All ____ help normalize.\Question: Choose the right answer from options given a) three b) six c) two d) one

Ex Output:
a


Ex Input:
Infants weigh on average ____ or two pounds at birth.\Question: Choose the right answer from options given a) one b) three c) seven d) eight

Ex Output:

a