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: find the smallest number that should be multiplied with 54000 to make it a perfect cube.
Options: ['a. 4', 'b. 5', 'c. 6', 'd. 3', 'e. 7']
Example Output: a

Example Input: Problem: the perimeter of a triangle is 40 cm and the inradius of the triangle is 2.5 cm. what is the area of the triangle ?
Options: a. 87 cm 2, b. 28 cm 2, c. 98 cm 2, d. 26 cm 2, e. 50 cm 2
Example Output: e

Example Input: Problem: when a merchant imported a certain item, she paid a 7 percent import tax on the portion of the total value of the item in excess of $ 1,000. if the amount of the import tax that the merchant paid was $ 109.20, what was the total value of the item ?
Options: a. $ 1,600, b. $ 1,850, c. $ 2,250, d. $ 2,440, e. $ 2,560
Example Output:
e