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 Q]: Problem: there are 15 balls in a jar. you take out 3 blue balls without putting them back inside, and now the probability of pulling out a blue ball is 1 / 3. how many blue balls were there in the beginning ?
Options: a. 12., b. 9., c. 8., d. 7., e. 6.
[EX A]: d

[EX Q]: Problem: out of 40 applicants to a law school, 15 majored in political science, 20 had a grade point average higher than 3.0, and 10 did not major in political science and had a gpa equal to or lower than 3.0. how many e applicants majored in political science and had a gpa higher than 3.0 ?
Options: a. 5, b. 10, c. 15, d. 25, e. 35
[EX A]: a

[EX Q]: Problem: if n is a positive integer and n ^ 2 is divisible by 36, then the largest positive integer that must divide n is
Options: a. 6, b. 12, c. 24, d. 36, e. 48
[EX A]:
a