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: Calves can browse and follow their mother at three weeks old and are weaned at ____ months.\Question: Choose the right answer from options given a) five b) seven c) four d) three
Example Output: a

Example Input: Many comets have ____ tails.\Question: Choose the right answer from options given a) two b) six c) three d) one
Example Output: a

Example Input: Shotguns range in weight from about five pounds to ____ pounds.\Question: Choose the right answer from options given a) zero b) eight c) five d) two
Example Output:
b