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: Insects have ____ common types of metamorphosis.\Question: Choose the right answer from options given a) six b) eight c) two d) seven
Example Output: c

Example Input: Fryers have ____ thermostats.\Question: Choose the right answer from options given a) five b) three c) two d) one
Example Output: c

Example Input: All insects have to have ____ legs.\Question: Choose the right answer from options given a) three b) six c) two d) eight
Example Output:
b