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 train of length 250 m crosses a bridge of length 150 m in 20 seconds. what is the speed of train ?
Options: a. 33, b. 27, c. 25, d. 22, e. 72
Example Output: e

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: two trains 500 m and 750 m long run at the speed of 60 km / hr and 40 km / hr respectively in opposite directions on parallel tracks. the time which they take to cross each other is ?
Options: a. 10.6, b. 45, c. 10.4, d. 10.8, e. 10.1
Example Output:
b