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: if the simple interest on a certain sum of money for 6 years is one – fifth of the sum, then the rate of interest per annum is
Options: a. 3.3 %, b. 7.2 %, c. 6.1 %, d. 5.0 %, e. 3.1 %

Ex Output:
a


Ex Input:
Problem: heinz produces tomato puree by boiling tomato juice. the tomato puree has only 20 % water while the tomato juice has 90 % water. how many liters of tomato puree will be obtained from 25 litres of tomato juice ?
Options: a. 2.8 liters., b. 3.125 liters., c. 8.5 liters., d. 2.6 liters., e. 2.1 liters.

Ex Output:
b


Ex Input:
Problem: x and y are two towns. ganesh covers the distance from x to y at an average speed of 43 km / hr. however, he covers the distance from y to x at an average speed of 34 km / hr. his average speed during the whole journey in km / hr. is :
Options: a. 34, b. 43, c. 40, d. 38, e. 29

Ex Output:

d