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: an aeroplane covers a certain distance at a speed of 150 kmph in 2 hours. to cover the same distance in 1 2 / 3 hours, it must travel at a speed of :
Options: a. 1300 kmph, b. 160 kmph, c. 180 kmph, d. 1080 kmph, e. none

Ex Output:
c


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: set a { 3, 3,3, 4,5, 5,5 } has a standard deviation of 1. what will the standard deviation be if every number in the set is multiplied by 8 ?
Options: a. a. 1, b. b. 2, c. c. 4, d. d. 8, e. e. 16

Ex Output:

d