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]: Where do good bacteria grow to help keep people healthy?  
 (A) in the brain (B) in the blood (C) on the skin (D) on the bones
[EX A]: C

[EX Q]: Which is an effect that cities have on the weather?  
 (A) Small numbers of plants cause rain to fall more often. (B) Large numbers of houses cause the wind to be stronger. (C) Small areas of open water cause fog to be more common. (D) Large areas of pavement cause the temperature to be hotter.
[EX A]:
D