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 sum of the ages of 5 children born at the intervals of 3 year each is 60 year. what is the age of the youngest child ?
Options: a. 4 year, b. 6 year, c. 10 year, d. none of these, e. 9 year

Ex Output:
b


Ex Input:
Problem: a 11 % stock yields 8 %. the market value of the stock is :
Options: a. rs. 72, b. rs. 137.50, c. rs. 112.50, d. rs. 116.50, e. none of these

Ex Output:
b


Ex Input:
Problem: a train covers a distance at a speed of 240 kmph in 5 hours. to cover the same distance in 5 / 3 hours, it must travel at a speed of ?
Options: a. 516, b. 840, c. 560, d. 720, e. 920

Ex Output:

d