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:
Mosquitoes spend one to ____ days in the pupae stage.\Question: Choose the right answer from options given a) zero b) two c) five d) three

Ex Output:
b


Ex Input:
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

Ex Output:
b


Ex Input:
Menses usually occurs for a period of ____ days, after which the preliferative stage begins.\Question: Choose the right answer from options given a) five b) no c) zero d) eight

Ex Output:

a