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 train 100 meters long completely crosses a 300 meters long bridge in 36 seconds. what is the speed of the train is ?
Options: a. 32 kmph, b. 76 kmph, c. 34 kmph, d. 43 kmph, e. 40 kmph
Example Output: e

Example Input: Problem: sheila works 8 hours per day on monday, wednesday and friday, and 6 hours per day on tuesday and thursday. she does not work on saturday and sunday. she earns $ 360 per week. how much does she earn in dollars per hour ?
Options: a. 11, b. 10, c. 9, d. 8, e. 7
Example Output: b

Example Input: Problem: a number x is multiplied by 3, and this product is then divided by 7. if the positive square root of the result of these two operations equals x, what is the value of x if x ≠ 0 ?
Options: a. 25 / 9, b. 3 / 7, c. 5 / 3, d. 3 / 5, e. 9 / 25
Example Output:
b