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: Traditional neon electrifies the inert gas from ____ directions.\Question: Choose the right answer from options given a) two b) nine c) one d) six
Example Output: a

Example Input: Habitat destruction is a concern for all ____ gorilla subspecies.\Question: Choose the right answer from options given a) no b) four c) three d) five
Example Output: b

Example Input: Racers refer to ____ types of oval tracks.\Question: Choose the right answer from options given a) seven b) three c) no d) nine
Example Output:
b