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: two trains, one from howrah to patna and the other from patna to howrah, start simultaneously. after they meet, the trains reach their destinations after 10 hours and 8 hours respectively. the ratio of their speeds is
Options: a. 4: 9, b. 4: 3, c. 4: 12, d. 4: 8, e. 4: 5

Ex Output:
e


Ex Input:
Problem: of all the homes on gotham street, 1 / 3 are termite - ridden, and 4 / 7 of these are collapsing. what fraction of the homes are termite - ridden, but not collapsing ?
Options: a. 1 / 3, b. 1 / 4, c. 1 / 5, d. 1 / 6, e. 1 / 7

Ex Output:
e


Ex Input:
Problem: the speed of a train is 90 kmph. what is the distance covered by it in 12 minutes ?
Options: a. 15, b. 18, c. 77, d. 52, e. 42

Ex Output:

b