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:
Western culture offers only ____ genders, man or woman.\Question: Choose the right answer from options given a) three b) two c) one d) four

Ex Output:
b


Ex Input:
Vaccination typically occurs at ____ to eight weeks of age in kittens.\Question: Choose the right answer from options given a) three b) nine c) six d) no

Ex Output:
c


Ex Input:
Atoms are extremely small, on the order of a few ____ billionths of a meter.\Question: Choose the right answer from options given a) ten b) seven c) nine d) eight

Ex Output:

a