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: a store sells chairs and tables. if the price of 2 chairs and 1 table is 60 % of the price of 1 chair and 2 tables, and the price of 1 table and 1 chair is $ 64, what is the price, in dollars, of 1 table ? ( assume that every chair has the same price and every table has the same price. )
Options: a. 48, b. 52, c. 54, d. 58, e. 56

Ex Output:
e

Ex Input:
Problem: when positive integer n is divided by 3, the remainder is 1. when n is divided by 7, the remainder is 5. what is the smallest positive integer k such that k + n is a multiple of 21 ?
Options: a. 2, b. 4, c. 6, d. 8, e. 10

Ex Output:
a

Ex Input:
Problem: in a bag of small balls 1 / 4 are green, 1 / 8 are blue, 1 / 12 are yellow and the remaining 26 white. how many balls are blue ?
Options: a. 6, b. 5, c. 4, d. 3, e. 8

Ex Output:
a