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: 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: bottle r contains 350 capsules and costs $ 6.25. bottle t contains 130 capsules and costs $ 2.99. what is the difference between the cost per capsule for bottle r and the cost per capsule for bottle t ?
Options: a. $ 0.25, b. $ 0.12, c. $ 0.0052, d. $ 0.003, e. $ 0.002

Ex Output:
c


Ex Input:
Problem: the total age of a and b is 12 years more than the total age of b and c. c is how many year younger than a
Options: a. 11, b. 12, c. 13, d. 14, e. 15

Ex Output:

b