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: Southern moles are six to ____ inches long and weigh three to four ounces.\Question: Choose the right answer from options given a) zero b) nine c) five d) seven
Example Output: d

Example Input: Female bilbies have a backward-opening pouch with ____ nipples.\Question: Choose the right answer from options given a) no b) two c) five d) eight
Example Output: d

Example Input: Scuba diving requires a certification which takes about ____ days to complete.\Question: Choose the right answer from options given a) one b) eight c) four d) ten
Example Output:
c