TASK DEFINITION: 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').
PROBLEM: Some male fish return after just ____ years.\Question: Choose the right answer from options given a) no b) two c) one d) six

SOLUTION: b

PROBLEM: Pairs encodes all sets of objects with ____ components.\Question: Choose the right answer from options given a) ten b) five c) two d) no

SOLUTION: c

PROBLEM: Plants lose vigor and decline in abundance within ____ to four years.\Question: Choose the right answer from options given a) three b) zero c) five d) two

SOLUTION:
a