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: ages of two persons differ by 20 years. if 6 year ago, the elder one be 3 times as old the younger one, find their present age
Options: a. 12,28, b. 14,30, c. 16,36, d. 18,34, e. 19,34

Ex Output:
c


Ex Input:
Problem: the present population of a town is 2000. population increase rate is 20 % p. a. find the population of town after 1 years ?
Options: a. 1000, b. 2400, c. 1500, d. 1600, e. 1250

Ex Output:
b


Ex Input:
Problem: 1 blue dice and 2 red dice are thrown.... what is the probability that the no. appeared on blue dice is always greater than both the no. appeared on the 2 red dice..
Options: a. 55 / 216, b. 56 / 216, c. 57 / 216, d. 54 / 216, e. 53 / 216

Ex Output:

a