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: Corn borers complete at least ____ generations each summer.\Question: Choose the right answer from options given a) zero b) three c) two d) ten
Example Output: c

Example Input: Cheetahs reach sexual maturity at around ____ years of age.\Question: Choose the right answer from options given a) two b) ten c) four d) nine
Example Output:
a