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: Chlorine gives vinyl ____ advantages.\Question: Choose the right answer from options given a) six b) four c) two d) ten
Example Output: c

Example Input: Granite occurs in ____ separate masses.\Question: Choose the right answer from options given a) two b) eight c) nine d) no
Example Output: a

Example Input: Worms have ____ main characteristics.\Question: Choose the right answer from options given a) three b) eight c) ten d) two
Example Output:
d