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.

Ex Input:
Problem: points a, b, c, and d, in that order, lie on a line. if ab = 3 cm, ac = 4 cm, and bd = 8 cm, what is cd, in centimeters ?
Options: a. 7, b. 2, c. 3, d. 4, e. 5

Ex Output:
a


Ex Input:
Problem: there are 15 boys and 10 girls in a class. if three students are selected at random, in how many ways that 1 girl or 2 boys are selected ?
Options: a. 100, b. 105, c. 115, d. 120, e. 125

Ex Output:
c


Ex Input:
Problem: a triangle and a parallelogram are constructed on the same base such that their areas are equal. if the altitude of the parallelogram is 100 m, then the altitude of the triangle is.
Options: ['a. 10 √ 2 m', 'b. 100 m', 'c. 100 √ 2 m', 'd. 200 m', 'e. none']

Ex Output:

d