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]: 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
[A]: b


[Q]: Taste is comprised of ____ primary senses detected on the palate.\Question: Choose the right answer from options given a) two b) seven c) five d) ten
[A]: c


[Q]: Squirrels have ____ teeth in the front of their mouth that constantly grow throughout their lives.\Question: Choose the right answer from options given a) eight b) four c) ten d) nine
[A]:
b