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: the perimeter of an isosceles right triangle is 12 + 12 sq rt 2. what is the length of the hypotenuse of the triangle ?
Options: ['a. 5', 'b. 6', 'c. 7', 'd. 8.485', 'e. 8']
Example Output: d

Example Input: Problem: a mixture of 70 litres of milk and water contains 10 % water. how many litres of water should be added to the mixture so that the mixture contains 12 1 / 2 % water ?
Options: a. 2, b. 8, c. 6, d. 3, e. 4
Example Output: a

Example Input: Problem: m = { - 6, - 5, - 4, - 3, - 2 } t = { - 2, - 1, 1, 2, 3 } if an integer is to be randomly selected from set m above and an integer is to be randomly selected from set t above, what is the probability that the product of the two integers will be negative ?
Options: a. 0, b. 1 / 3, c. 2 / 5, d. 1 / 2, e. 3 / 5
Example Output:
e