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: an automobile parts supplier charges $ 25 per package of gaskets. when a customer orders more than 10 packages of gaskets, the supplier charges 4 / 5 the price for each package in excess of 10. during a certain week, the supplier sold 60 packages of gaskets. if 15 percent of the gaskets went to company x, 15 percent to company y, and the rest to company z, what was the total amount, in dollars, that the parts supplier received in payment for the gaskets ?
Options: a. 1340, b. 1445, c. 1375, d. 1415, e. 1455

Ex Output:
a

Ex Input:
Problem: find the area of a parallelogram with base 10 cm and height 20 cm.
Options: a. 200, b. 384, c. 200, d. 244, e. 242

Ex Output:
c

Ex Input:
Problem: a copy machine, working at a constant rate, makes 35 copies per minute. a second copy machine, working at a constant rate, makes 65 copies per minute. working together at their respective rates, how many copies do the two machines make in half an hour ?
Options: a. 3,000, b. 2,700, c. 4,500, d. 5,400, e. 324,000

Ex Output:
a