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: All spider mites have ____ legs and a lack of a separate head.\Question: Choose the right answer from options given a) eight b) four c) ten d) one
Example Output: a

Example Input: Voles are prolific breeders and can produce four to ____ litters a year.\Question: Choose the right answer from options given a) four b) two c) six d) three
Example Output: c

Example Input: Hindu myths imagine the universe being upheld by ____ elephants standing on a turtle's back.\Question: Choose the right answer from options given a) four b) no c) five d) two
Example Output:
a