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.

Example Input: Problem: sandy walked 20 meters towards south. then sandy turned to her left and walked 20 meters. she then turned to her left and walked 20 meters. she then turned to her right and walked 25 meters. what distance is she from the starting point and in which direction ?
Options: a. 35 m east, b. 35 m north, c. 30 m west, d. 45 m west, e. 45 m east
Example Output: e

Example 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
Example Output: d

Example Input: Problem: on a certain farm the ratio of horses to cows is 4: 1. if the farm were to sell 15 horses and buy 15 cows, the ratio of horses to cows would then be 13: 7. after the transaction, how many more horses than cows would the farm own ?
Options: a. 30, b. 60, c. 75, d. 90, e. 105
Example Output:
a