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 car is 15 minutes late by running at a speed of 4 / 5 th of its actual speed. the actual time taken by the car to cover that distance is :
Options: a. 30 minutes, b. 1 hour, c. 2 hours, d. 3 hours, e. none of these

Ex Output:
b


Ex Input:
Problem: barbata invests $ 2200 in the national bank at 5 %. how much additional money must she invest at 8 % so that the total annual income will be equal to 6 % of her entire investment ?
Options: a. 1100, b. 3000, c. 1000, d. 3600, e. 2400

Ex Output:
a


Ex Input:
Problem: if the cost price of 18 articles is same as the selling price of 25 articles. find the gain or loss percentage ?
Options: a. 30 % gain, b. 28 % loss, c. 40 % gain, d. 40 % loss, e. 50 % loss

Ex Output:

b