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 sources claim there are more like ____ million vertebrate animals in zoos.\Question: Choose the right answer from options given a) six b) five c) one d) three

SOLUTION: b

PROBLEM: Fever usually lasts for an average of ____ days in adults.\Question: Choose the right answer from options given a) zero b) three c) nine d) two

SOLUTION: b

PROBLEM: Human life develops or evolves in ____ stages.\Question: Choose the right answer from options given a) seven b) six c) eight d) two

SOLUTION:
a