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 man spends 2 / 5 of his salary on house rent, 3 / 10 of his salary on food and 1 / 8 of his salary on convenience he has rs. 1400 left with him, find his expenditure on food and conveyance.
Options: a. 1000, b. 3000, c. 4000, d. 2000, e. 5000

Ex Output:
a


Ex Input:
Problem: the speed of the boat in still water in 12 kmph. it can travel downstream through 48 kms in 3 hrs. in what time would it cover the same distance upstream ?
Options: a. 8 hours, b. 6 hours, c. 4 hours, d. 5 hours, e. 6 hours

Ex Output:
e


Ex Input:
Problem: a certain rectangular crate measures 6 feet by 8 feet by 10 feet. a cylindrical gas tank is to be made for shipment in the crate and will stand upright when the crate is placed on one of its six faces. what should the radius of the tank be if it is to be of the largest possible volume ?
Options: a. 4, b. 4, c. 6, d. 8, e. 10

Ex Output:

b