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: 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: Bloody diarrhea lasts for two to ____ days.\Question: Choose the right answer from options given a) nine b) five c) three d) no
Example Output: b

Example Input: Triadic combinations involve ____ colors.\Question: Choose the right answer from options given a) no b) seven c) three d) eight
Example Output:
c