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.
Q: Problem: if 5 % more is gained by selling an article for rs. 360 than by selling it for rs. 340, the cost of the article is ?
Options: a. 127, b. 688, c. 400, d. 121, e. 123
A: 
c