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: Pups remain in the den for about ____ weeks, and are cared for by the entire pack.\Question: Choose the right answer from options given a) ten b) three c) six d) no
Example Output: c

Example Input: Paleontologists specialize in ____ main areas.\Question: Choose the right answer from options given a) eight b) five c) no d) six
Example Output: b

Example Input: Many people say the ruminant has ____ stomachs.\Question: Choose the right answer from options given a) zero b) four c) one d) eight
Example Output:
b