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.
--------
Question: 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

Answer: c


Question: Problem: an article is bought for rs. 675 and sold for rs. 900, find the gain percent ?
Options: a. 33 1 / 8 %, b. 33 9 / 3 %, c. 33 1 / 3 %, d. 93 1 / 3 %, e. 33 2 / 3 %

Answer: c


Question: Problem: excluding the stoppages, the speed of a bus is 12 km / hr and including the stoppages the speed of the bus is 6 km / hr. for how many minutes does the bus stop per hour ?
Options: a. 15 min, b. 30 min, c. 12 min, d. 20 min, e. 18 min

Answer:
b