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: Prairie dogs bear four or ____ young per litter.\Question: Choose the right answer from options given a) five b) eight c) two d) zero
Example Output: a

Example Input: Songbirds have ____ sets of vocal chords.\Question: Choose the right answer from options given a) six b) two c) eight d) ten
Example Output: b

Example Input: Tapirs have hoofed toes, with four toes on the front feet and ____ toes on the hind feet.\Question: Choose the right answer from options given a) four b) three c) one d) no
Example Output:
b