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').

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


[Q]: Birds have ____ eyes.\Question: Choose the right answer from options given a) eight b) five c) nine d) two
[A]: d


[Q]: Banks merge and change their names at least every once every ____ year.\Question: Choose the right answer from options given a) five b) ten c) eight d) one
[A]:
a