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]: Plants can uptake ____ times more nutrients, and improve soil texture at the same time.\Question: Choose the right answer from options given a) no b) two c) three d) ten
[A]: d


[Q]: Wolverines reproduce every ____ or three years.\Question: Choose the right answer from options given a) two b) three c) one d) four
[A]: a


[Q]: Today there are ____ federal states, each based on cultural affiliations.\Question: Choose the right answer from options given a) one b) nine c) seven d) zero
[A]:
b