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: Human rabies is extremely rare, and there have been no cases in Oregon in the last ____ years.\Question: Choose the right answer from options given a) nine b) five c) ten d) eight
Example Output: d

Example Input: Tardigrades are microscopic, water-dwelling, segmented animals with ____ legs.\Question: Choose the right answer from options given a) eight b) nine c) one d) seven
Example Output: a

Example Input: Immune response improves in about ____ weeks.\Question: Choose the right answer from options given a) six b) no c) four d) three
Example Output:
c