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:
Human females have ____ X chromosomes.\Question: Choose the right answer from options given a) two b) six c) one d) eight

Ex Output:
a


Ex Input:
Breast cancer strikes one out of every ____ American women.\Question: Choose the right answer from options given a) one b) nine c) no d) six

Ex Output:
b


Ex Input:
Bovine insulin differs from human in only ____ amino acid residues, and porcine insulin in one.\Question: Choose the right answer from options given a) six b) one c) three d) zero

Ex Output:

c