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: Ruminants have an even number of toes on each foot and a stomach with either three or ____ chambers.\Question: Choose the right answer from options given a) four b) two c) seven d) five
Example Output: a

Example Input: Humans learn through the ____ senses.\Question: Choose the right answer from options given a) eight b) one c) five d) ten
Example Output: c

Example Input: Most insects have ____ antennae, six legs, and four wings.\Question: Choose the right answer from options given a) four b) three c) six d) two
Example Output:
d