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: Diploid cultivars have ____ alleles.\Question: Choose the right answer from options given a) eight b) six c) two d) five
Example Output: c

Example Input: Ozone is a naturally occurring molecule containing ____ atoms of oxygen.\Question: Choose the right answer from options given a) three b) five c) nine d) eight
Example Output: a

Example Input: Permanent dentition is in place after ____ years of age.\Question: Choose the right answer from options given a) one b) zero c) four d) nine
Example Output:
c