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: a trader sells 85 meters of cloth for rs. 8500 at the profit of rs. 15 per metre of cloth. what is the cost price of one metre of cloth ?
Options: a. rs. 80, b. rs. 85, c. rs. 90, d. rs. 95, e. none of these
Output:
b