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: Most linguists organize the African languages into ____ major language families.\Question: Choose the right answer from options given a) three b) four c) eight d) no
Example Output: b

Example Input: Trappers have ____ genders and reproduce sexually.\Question: Choose the right answer from options given a) zero b) two c) five d) one
Example Output: b

Example Input: Ring modulation is the multiplication of ____ signals.\Question: Choose the right answer from options given a) zero b) nine c) six d) two
Example Output:
d