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 person buys an article at $ 600. at what price should he sell the article so as to make a profit of 8 % ?
Options: a. 670, b. 689, c. 648, d. 740, e. 889

Output: c


Input: Consider Input: Problem: a couple who own an appliance store discover that if they advertise a sales discount of 10 % on every item in the store, at the end of one month the number of total items sold increases 15 %. their gross income from sales for one month increases by what percent ?
Options: a. 1.5 %, b. 2.5 %, c. 3.5 %, d. 4.5 %, e. 5.5 %

Output: c


Input: Consider Input: Problem: a and b can finish a work in 10 days while b and c can do it in 18 days. a started the work, worked for 5 days, then b worked for 10 days and the remaining work was finished by c in 15 days. in how many days could c alone have finished the whole work ?
Options: a. 30 days, b. 15 days, c. 45 days, d. 24 days, e. none of these


Output: c