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.

Input: Consider Input: Problem: the diagonal of a rectangle is √ 41 cm and its area is 20 sq. cm. the perimeter of the rectangle must be :
Options: ['a. 18', 'b. 28', 'c. 38', 'd. 48', 'e. 58']

Output: a


Input: Consider Input: Problem: 10, 1000, 100000, 10000000....
Options: a. 100, 000,000, b. 1,000, 000,000, c. 1, 000,000, 000,000, d. 100, e. 1, 000,000

Output: b


Input: Consider Input: Problem: a patient is given exactly 750 milliliters of a mixture of two medications daily. medication a contains 40 % pain killer and medication b contains 20 % pain killer. if the patient receives exactly 215 milliliters of pain killer daily, how many milliliters of medication b are in the mixture ?
Options: a. 150, b. 225, c. 325, d. 425, e. 550


Output: d