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: Fruit trees are usually safe after ____ years.\Question: Choose the right answer from options given a) five b) four c) no d) three
Example Output: d

Example Input: Insects have ____ pairs of legs and three body segments.\Question: Choose the right answer from options given a) one b) nine c) no d) three
Example Output: d

Example Input: Human knowledge is limited to what can be experience with the ____ senses.\Question: Choose the right answer from options given a) zero b) three c) five d) one
Example Output:
c