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: sakshi can do a piece of work in 5 days. tanya is 25 % more efficient than sakshi. the number of days taken by tanya to do the same piece of work :
Options: a. 4, b. 16, c. 18, d. 25, e. 10
Example Output: a

Example Input: Problem: at joes steakhouse the hourly wage for a chef is 20 % greater than that of a dishwasher, and the hourly wage of a dishwasher is half as much as the hourly wage of a manager. if a managers wage is $ 6.50 per hour, how much less than a manager does a chef earn each hour ?
Options: a. $ 2.6, b. $ 2.40, c. $ 3.40, d. $ 4.40, e. $ 5.40
Example Output: a

Example Input: Problem: a cistern 8 m long and 4 m wide contains water up to a depth of 1 m 25 cm. the total area of the wet surface is :
Options: a. 62 m 2, b. 50 m 2, c. 53.5 m 2, d. 55 m 2, e. 57 m 2
Example Output:
a