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 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 %

Ex Output:
c


Ex Input:
Problem: the dimensions of a room are 25 feet * 15 feet * 12 feet. what is the cost of white washing the four walls of the room at rs. 10 per square feet if there is one door of dimensions 6 feet * 3 feet and three windows of dimensions 4 feet * 3 feet each ?
Options: a. s. 9060, b. s. 4520, c. s. 4527, d. s. 4530, e. s. 4521

Ex Output:
a


Ex Input:
Problem: the average salary of all the workers in a workshop is rs. 8000. the average salary of 7 technicians is rs. 11000 and the average salary of the rest is rs. 6000. the total number of workers in the workshop is
Options: a. 14, b. 21, c. 22, d. 23, e. none

Ex Output:

a