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: 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 age of 8 men increases by 2 years when two women are included in place of two men of ages 20 and 22 years. find the average age of the women ?
Options: a. 87, b. 98, c. 30, d. 29, e. 37

Ex Output:
d

Ex Input:
Problem: a mixture of 150 liters of wine and water contains 15 % water. how much more water should be added so that water becomes 25 % of the new mixture ?
Options: a. 10, b. 30, c. 20, d. 15, e. 17

Ex Output:
c