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 are born ____ and a half months after mating.\Question: Choose the right answer from options given a) six b) ten c) eight d) two
Example Output: c

Example Input: Condors become sexually mature at about five or ____ years of age and mate for life.\Question: Choose the right answer from options given a) nine b) seven c) one d) six
Example Output: d

Example Input: Plants grow approximately ____ to ten feet tall.\Question: Choose the right answer from options given a) eight b) two c) one d) six
Example Output:
d