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: a 270 metres long bullet train running at the speed of 120 kmph crosses another bullet train running in opposite direction at the speed of 80 kmph in 9 seconds. what is the length of the other bullet train ?
Options: a. 226, b. 230, c. 430, d. 310, e. 260
Example Output: b

Example Input: Problem: find the simple interest on rs. 72,000 at 16 2 / 3 % per year for 9 months.
Options: a. 7500, b. 6500, c. 9000, d. 9500, e. none of them
Example Output: c

Example Input: Problem: a shopkeeper has 280 kg of apples. he sells 85 % of these at 20 % profit and remaining 60 % at 30 % profit. find his % profit on total.
Options: a. 24 %, b. 25 %, c. 26 %, d. 28 %, e. 35 %
Example Output:
e