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]: Similar types of cells form tissues. What is the next level of complexity formed from the grouping of tissues?
(A) organs (B) organelles (C) organisms (D) organ systems
[EX A]: A

[EX Q]: The human immunodeficiency virus (HIV) causes AIDS. The first known human cases AIDS were in Africa in the late 1950s. Since then, tens of millions of people have died from the disease, and tens of millions more people all over the world are infected. Which term best describes the disease AIDS?
(A) isolated cases (B) outbreak (C) epidemic (D) pandemic
[EX A]: D

[EX Q]: A girl with long hair is going to be participating in an experiment that uses an alcohol burner for an energy source. What is the best thing for her to do to prepare for this experiment?
(A) leave her large jacket in her locker for the day (B) use goggles during the experiment (C) tie her hair back away from her face (D) wear a lab apron during the experiment
[EX A]:
C