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: mary works in a restaurant a maximum of 70 hours. for the first 20 hours, she is paid $ 8 per hour. for each overtime hour, she is paid at a rate which is 25 % higher than her regular rate. how much mary can earn in a week ?
Options: a. 600, b. 620, c. 660, d. 320, e. 400
Example Output: c

Example Input: Problem: a is twice as good a work man as b and together they finish the work in 4 days. in how many days a alone can finish the work ?
Options: a. 3, b. 2, c. 7, d. 9, e. 6
Example Output: e

Example Input: Problem: if 4 men can colour 48 m long cloth in 2 days, then 2 men can colour 36 m long cloth in
Options: a. 1 day, b. 2 days, c. 3 days, d. 4 days, e. 5 days
Example Output:
c