You will be given a definition of a task first, then some input of the task.
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.

Problem: by selling an article at rs. 600, a shopkeeper makes a profit of 25 %. at what price should he sell the article so as to make a loss of 25 % ?
Options: a. s. 360, b. s. 480, c. s. 500, d. s. 450, e. s. 550
Output:
a