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: heinz produces tomato puree by boiling tomato juice. the tomato puree has only 20 % water while the tomato juice has 90 % water. how many liters of tomato puree will be obtained from 25 litres of tomato juice ?
Options: a. 2.8 liters., b. 3.125 liters., c. 8.5 liters., d. 2.6 liters., e. 2.1 liters.

Ex Output:
b


Ex Input:
Problem: for each color copy, print shop x charges $ 1.20 and print shop y charges $ 1.70. how much greater is the charge for 40 color copies at print shop y than at print shop x ?
Options: a. $ 14, b. $ 16, c. $ 18, d. $ 20, e. $ 22

Ex Output:
d


Ex Input:
Problem: a total of $ 20,000 was invested in two certificates of deposit at simple annual interest rates of 6 percent and 12 percent, respectively. if the total interest on the two certificates was $ 1,440 at the end of one year, what fractional part of the $ 20.000 was invested at the higher rate ?
Options: a. 3 / 8, b. 2 / 5, c. 1 / 5, d. 3 / 5, e. 3 / 4

Ex Output:

c