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: Matter exists in ____ forms, solid, fluid and plasma.\Question: Choose the right answer from options given a) ten b) nine c) three d) five
Example Output: c

Example Input: Ascidian tunicates come in ____ main forms.\Question: Choose the right answer from options given a) three b) zero c) four d) eight
Example Output: a

Example Input: Wolves can go ____ weeks without feeding.\Question: Choose the right answer from options given a) four b) three c) eight d) seven
Example Output:
b