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').

Example Input: Eastern cottontails have ____ different fur coats each year.\Question: Choose the right answer from options given a) five b) two c) eight d) six
Example Output: b

Example 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
Example Output: b

Example Input: Vaccines come in ____ different forms, live and inactive.\Question: Choose the right answer from options given a) nine b) two c) eight d) seven
Example Output:
b