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: if x ^ 2 – 3 x = 18, then one possible value of x – 4 =
Options: a. - 9, b. - 5, c. - 3, d. - 1, e. 2
Example Output: e

Example Input: Problem: one side of a rectangular field is 14 m and one of its diagonal is 17 m. find the area of the field.
Options: a. 134.4, b. 120, c. 150, d. 180, e. none
Example Output: a

Example Input: Problem: the average of 25 results is 20. the average of first 12 of those is 14 and the average of last 12 is 17. what is the 13 th result ?
Options: a. 128, b. 75, c. 69, d. 78, e. 45
Example Output:
a