Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Example Input: Problem: a fraudulent dairy guy declares to market his dairy at price range but he combined it with water and therefore benefits 25 %. the percentage of water in the combination is :
Options: a. 20 %, b. 30 %, c. 50 %, d. 35 %, e. 60 %
Example Output: a

Example Input: Problem: a cricket player whose bowling average was 23.50 runs per wicket, takes 5 wicket for 52 runs in a match. due to this his average decreases by 0.50. what will be the number of wickets taken by him till the last match ?
Options: a. 64, b. 72, c. 131, d. 456, e. 108
Example Output: c

Example Input: Problem: for each color copy, print shop x charges $ 1.25 and print shop y charges $ 2.75. how much greater is the charge for 40 color copies at print shop y than at print shop x ?
Options: a. $ 48, b. $ 54, c. $ 60, d. $ 66, e. $ 72
Example Output:
c