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 train of 25 carriages, each of 60 meters length, when an engine also of 60 meters length is running at a speed of 60 kmph. in what time will the train cross a bridge 1.0 km long ?
Options: a. 2.5, b. 3, c. 5, d. 7, e. 9

Ex Output:
a


Ex Input:
Problem: find the greatest number which leaves the same remainder when it divides 16, 46 and 82.
Options: a. 18, b. 8, c. 12, d. 16, e. none of these

Ex Output:
e


Ex Input:
Problem: two numbers are in the ratio 3: 5. if 9 be subtracted from each, they are in the ratio of 1: 2. the first number is :
Options: a. a. 27, b. b. 98, c. c. 34, d. d. 35, e. e. 62

Ex Output:

a