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: a certain protective additive increases from 50 days to 60 days the time between required maintenance checks on an industrial vehicle. by what percent is the time between maintenance checks increased by using the additive ?
Options: a. 25 %, b. 33 1 / 3 %, c. 50 %, d. 66 2 / 3 %, e. 20 %

Answer: e


Question: Problem: what is the smallest positive integer x such that 66 - x is the cube of a positive integer
Options: a. 5, b. 7, c. 47, d. 9, e. 2

Answer: e


Question: Problem: in may, the groundskeeper at spring lake golf club built a circular green with an area of 65 π square feet. in august, the groundskeeper doubled the distance from the center of the green to the edge of the green. what is the total area of the renovated green ?
Options: a. 105 π, b. 130 π, c. 200 π, d. 260 π, e. 320 π

Answer:
d