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.

Input: Consider Input: Problem: a sum of money at simple interest amounts to rs. 720 after 2 years and to rs. 1020 after a further period of 5 years. the sum is :
Options: a. 400, b. 500, c. 600, d. 700, e. 800

Output: c


Input: Consider Input: Problem: exactly 35 % of the reporters for a certain wire service cover local politics in country x. if 30 % of the reporters who cover politics for the wire service do not cover local politics in country x, what percent of the reporters for the wire service do not cover politics ?
Options: a. 20 %, b. 42 %, c. 44 %, d. 50 %, e. 84 %

Output: d


Input: Consider Input: Problem: of the 200 stamps in a collection, 80 are foreign and 50 are more than 10 years old. if 20 stamps are both foreign and more than 10 years old, how many stamps are neither foreign nor more than 10 years old ?
Options: a. 60, b. 90, c. 100, d. 130, e. 150


Output: b