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.
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Question: 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

Answer: D


Question: In gym class a student kicks a soccer ball high into the air. As the ball goes upward, which type of energy is increasing?  
 (A) kinetic energy (B) thermal energy (C) potential energy (D) mechanical energy

Answer: C


Question: Christina kicks a ball. The ball moves faster when she kicks it on the concrete sidewalk than when she kicks it on the grass. Why does the ball travel slower on the grass than the sidewalk?  
 (A) The grass has more friction. (B) The grass attracts more wind. (C) The grass has a higher temperature. (D) The grass increases Earth's gravity.

Answer:
A