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: what is the smallest positive integer x such that 66 - x is the cube of a positive integer
Options: a. 5, b. 7, c. 47, d. 9, e. 2

Ex Output:
e


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: in what time will a train 175 m long cross an electric pole, it its speed be 180 km / hr ?
Options: a. 7.5, b. 6.5, c. 5.5, d. 4.5, e. 3.5

Ex Output:

e