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.

Input: Consider Input: 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

Output: c

Input: Consider Input: Problem: the price of a certain painting increased by 30 % during the first year and decreased by 15 % during the second year. the price of the painting at the end of the 2 - year period was what percent of the original price ?
Options: a. 102 %, b. 105 %, c. 110.5 %, d. 112.5 %, e. 100 %

Output: c

Input: Consider Input: Problem: a team p of 20 engineers can complete work or task in 32 days. another team q of 16 engineers can complete same task in 30 days. then the ratio of working capacity of 1 member of p to the 1 member of q is a. 3: 2
Options: a. 22, b. 34, c. 77, d. 29, e. 21
Output: b