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: given that p is a positive even integer with a positive units digit, if the units digit of p ^ 3 minus the units digit of p ^ 2 is equal to 0, what is the units digit of p + 4 ?
Options: a. 7, b. 8, c. 10, d. 11, e. 12
[EX A]: c

[EX Q]: Problem: if a person walks at 25 km / hr instead of 10 km / hr, he would have walked 20 km more. the actual distance traveled by him is :
Options: a. 50 km, b. 56 km, c. 13.3 km, d. 70 km, e. 80 km
[EX A]: c

[EX Q]: Problem: there are 200 female managers in a certain company. find the total number w of female employees in the company, if 2 / 5 of all the employees are managers and 2 / 5 of all male employees are managers.
Options: a. 300, b. w = 400, c. w = 500, d. w = 600, e. none of these
[EX A]:
c