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: Tribal peoples teach that there are ____ parts to any ceremony, each equally important.\Question: Choose the right answer from options given a) four b) nine c) ten d) seven
Example Output: a

Example Input: Manatees swim two to ____ miles per hour.\Question: Choose the right answer from options given a) no b) six c) five d) zero
Example Output: b

Example Input: Fire extinguishers have ____ parts.\Question: Choose the right answer from options given a) nine b) six c) zero d) seven
Example Output:
d