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 range q of the 6 numbers 4, 314, 710 and x is 12, what is the difference between the greatest possible value of x and least possible value of x ?
Options: a. 0, b. 2, c. 12, d. 13, e. 15

Ex Output:
d

Ex Input:
Problem: if 5 a = 3125, then the value of 5 ( a - 3 ) is :
Options: a. 25, b. 125, c. 625, d. 1625, e. none of these

Ex Output:
a

Ex Input:
Problem: the length of a train and that of a platform are equal. if with a speed of 36 k / hr, the train crosses the platform in one minute, then the length of the train ( in meters ) is ?
Options: a. 752, b. 799, c. 300, d. 750, e. 712

Ex Output:
c