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: Quadrupeds are animals with ____ feet, such as cows.\Question: Choose the right answer from options given a) four b) six c) ten d) two
Example Output: a

Example Input: Polyester has ____ favorable properties.\Question: Choose the right answer from options given a) four b) two c) seven d) six
Example Output: b

Example Input: Height is controlled by at least ____ genes.\Question: Choose the right answer from options given a) four b) nine c) six d) eight
Example Output:
a