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.

Ex Input:
Problem: a train traveling at 72 kmph crosses a platform in 33 seconds and a man standing on the platform in 18 seconds. what is the length of the platform in meters ?
Options: a. 240 meters, b. 360 meters, c. 420 meters, d. 300 meters, e. can not be determined

Ex Output:
d


Ex Input:
Problem: the ` ` racing magic ' ' takes 120 seconds to circle the racing track once. the ` ` charging bull ' ' makes 40 rounds of the track in an hour. if they left the starting point together, how many minutes will it take for them to meet at the starting point for the second time ?
Options: a. 3, b. 6, c. 9, d. 12, e. 15

Ex Output:
d


Ex Input:
Problem: in a chess competition involving some men and women, every player needs to play exactly one game with every other player. it was found that in 45 games, both the players were women and in 190 games, both players were men. what is the number of games in which one person was a man and other person was a woman ?
Options: a. 40, b. 120, c. 180, d. 200, e. 220

Ex Output:

d