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]: Litters contain from one to ____ kittens, and tend to be much larger when prey is abundant.\Question: Choose the right answer from options given a) three b) four c) two d) seven
[A]: b


[Q]: Most children experience at least one episode by the time they are ____ years old.\Question: Choose the right answer from options given a) eight b) one c) ten d) seven
[A]: d


[Q]: Scientists use a characteristic to classify animals into ____ groups.\Question: Choose the right answer from options given a) three b) two c) five d) six
[A]:
b