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 speed of the boat in still water in 12 kmph. it can travel downstream through 54 kms in 3 hrs. in what time would it cover the same distance upstream ?
Options: a. 8 hours, b. 6 hours, c. 4 hours, d. 5 hours, e. 9 hours

Ex Output:
e


Ex Input:
Problem: a person incurs a loss of 5 % be selling a watch for rs. 1140. at what price should the watch be sold to earn 5 % profit
Options: a. rs. 1200, b. rs. 1230, c. rs. 1260, d. rs. 1290, e. none of these

Ex Output:
c


Ex Input:
Problem: a father said to his son, ` ` i was as old as you are at the present at the time of your birth ' '. if the father ' s age is 52 years now, the son ' s age 5 years back was :
Options: a. a. 14, b. b. 67, c. c. 56, d. d. 21, e. e. 34

Ex Output:

d