You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

[EX Q]: Wave energy from the ocean can be harnessed to power generators to make electricity. Energy from ocean tides can also be used to make electricity. How would you categorize these two sources of energy?
(A) Both are renewable. (B) Both are nonrenewable. (C) Wave energy is nonrenewable. Tidal energy is renewable. (D) Wave energy is renewable. Tidal energy is nonrenewable.
[EX A]: A

[EX Q]: Air is composed of many different substances. Which of the following components of air is a compound rather than an element?
(A) Argon, Ar (B) Oxygen, O2 (C) Water, H2O (D) Nitrogen, N2
[EX A]: C

[EX Q]: A mineral sample is obtained from a box, and acid is dropped on the sample to determine if it bubbles. Which best describes what should be done with the mineral after testing it?
(A) Return the mineral to its box. (B) Rinse the mineral with water, dry it, and return it to the box. (C) Wipe the mineral with a paper towel and return it to the box. (D) Put the mineral in the sink and leave it for the teacher to clean up.
[EX A]:
B