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:
Vision disorders affect one in every ____ school-age children.\Question: Choose the right answer from options given a) five b) four c) nine d) one

Ex Output:
b


Ex Input:
Tetrapods are animals that have ____ legs or leg-like appendages.\Question: Choose the right answer from options given a) four b) one c) ten d) six

Ex Output:
a


Ex Input:
Raptors usually have three talons pointing forward and ____ talon pointing backward.\Question: Choose the right answer from options given a) no b) seven c) one d) five

Ex Output:

c