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: 54671 - 14456 - 31466 = ?
Options: a. 2449, b. 5449, c. 8749, d. 8449, e. 6468

Ex Output:
c


Ex Input:
Problem: the perimeter of a triangle is 40 cm and the inradius of the triangle is 2.5 cm. what is the area of the triangle ?
Options: a. 87 cm 2, b. 28 cm 2, c. 98 cm 2, d. 26 cm 2, e. 50 cm 2

Ex Output:
e


Ex Input:
Problem: how many bricks, each measuring 25 cm x 11.25 cm x 6 cm, will be needed to build a wall of 8.5 m x 6 m x 22.5 cm ?
Options: a. 6400, b. 6410, c. 6440, d. 6500, e. 6800

Ex Output:

e