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: buses a and b start from a common bus stop x. bus a begins to travel in a straight line away from bus b at a constant rate of 30 miles per hour. one hour later, bus b begins to travel in a straight line in the exact opposite direction at a constant rate of 50 miles per hour. if both buses travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes bus b to cover the exact distance that bus a has covered and the amount of time it takes bus b to cover twice the distance that bus a has covered ?
Options: a. 36, b. 84, c. 132, d. 144, e. 180
Example Output: b

Example Input: Problem: if price of t. v set is reduced by 20 %, then its sale increases by 80 %, find net effect on sale value
Options: a. 44, b. 45, c. 46, d. 47, e. 48
Example Output: a

Example Input: Problem: the ratio between the length and the breadth of a rectangular park is 3: 2. if a man cycling along theoundary of the park at the speed of 12 km / hr completes one round in 8 min, then thearea of the park ( in sq. m ) is ?
Options: a. 124545 m, b. 134561 m, c. 156787 m, d. 15450 m, e. 153600 m
Example Output:
e