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: what will be the percentage increase in the area of the cube ' s surface if each of the cube ' s edges grows by 40 % ?
Options: a. 95 %, b. 90 %, c. 85 %, d. 96 %, e. 25 %

Ex Output:
d


Ex Input:
Problem: there are 27 different 3 - digit integers that can be formed using only the digits 3, 4 and 5. if all 27 of the integers were listed, what would their sum be ?
Options: a. 11,888, b. 11,988, c. 12,088, d. 12,188, e. 12,288

Ex Output:
b


Ex Input:
Problem: the length of the bridge, which a train 130 metres long and travelling at 54 km / hr can cross in 30 seconds, is :
Options: a. 200 m, b. 225 m, c. 320 m, d. 250 m, e. 240 m

Ex Output:

c