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: Baboons can travel up to ____ miles a day.\Question: Choose the right answer from options given a) seven b) three c) two d) six
Example Output: d

Example Input: Motor neurons are divided into ____ groups.\Question: Choose the right answer from options given a) two b) six c) seven d) eight
Example Output: a

Example Input: Protists are mostly microscopic and have ____ organs or tissues.\Question: Choose the right answer from options given a) no b) two c) six d) five
Example Output:
a