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: car x began traveling at an average speed of 35 miles per hour. after 72 minutes, car y began traveling at an average speed of 49 miles per hour. when both cars had traveled the same distance, both cars stopped. how many miles did car x travel from the time car y began traveling until both cars stopped ?
Options: a. 105, b. 120, c. 140, d. 147, e. 168

Ex Output:
a


Ex Input:
Problem: 50 % of a number is more than 40 % of 120 by 180. find the number ?
Options: a. 456, b. 480, c. 420, d. 445, e. 320

Ex Output:
a


Ex Input:
Problem: an exam consists of 8 true / false questions. brian forgets to study, so he must guess blindly on each question. if any score above 80 % is a passing grade, what is the probability that brian passes ?
Options: a. 1 / 16, b. 37 / 256, c. 1 / 2, d. 219 / 256, e. 125 / 256

Ex Output:

e