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.

Example Input: Problem: the purchase price of an article is $ 48. in order to include 5 % of cost for overhead and to provide $ 12 of net profit, the markup should be
Options: a. 15 %, b. 25 %, c. 30 %, d. 40 %, e. 45 %
Example Output: c

Example Input: Problem: maxwell leaves his home and walks toward brad ' s house. one hour later, brad leaves his home and runs toward maxwell ' s house. if the distance between their homes is 14 kilometers, maxwell ' s walking speed is 4 km / h, and brad ' s running speed is 6 km / h. what is the total time it takes maxwell before he meets up with brad ?
Options: a. 2, b. 4, c. 5, d. 6, e. 8
Example Output: a

Example Input: Problem: a fair price shopkeeper takes 10 % profit on his goods. he lost 60 % goods during theft. his loss percent is :
Options: a. 72 %, b. 42 %, c. 56 %, d. 12 %, e. 22 %
Example Output:
c