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.

Ex Input:
Problem: a furniture dealer purchased a desk for $ 150 and then set the selling price equal to the purchase price plus a markup that was 40 % of the selling price. if the dealer sold the desk at the selling price, what was the amount of the dealer ' s gross profit from the purchase and the sale of the desk ?
Options: a. $ 40, b. $ 60, c. $ 80, d. $ 90, e. $ 100

Ex Output:
e


Ex Input:
Problem: a certain library assesses fines for overdue books as follows. on the first day that a book is overdue, the total fine is $ 0.09. for each additional day that the book is overdue, the total fine is either increased by $ 0.30 or doubled, whichever results in the lesser amount. what is the total for a book on the fourth day it is overdue ?
Options: a. $ 0.66, b. $ 0.70, c. $ 0.80, d. $ 0.90, e. $ 1.00

Ex Output:
a


Ex Input:
Problem: heinz produces tomato puree by boiling tomato juice. the tomato puree has only 20 % water while the tomato juice has 90 % water. how many litres of tomato puree will be obtained from 20 litres of tomato juice ?
Options: a. 2 litres, b. 2.4 litres, c. 2.5 litres, d. 6 litres, e. 4 litres

Ex Output:

c