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.

[Q]: Which is the best example of something that has kinetic energy?  
 (A) a rock sitting at the top of a steep hill (B) a tennis ball rolling across the court (C) a picture hanging on the wall (D) a piece of wood before it is burned
[A]: B


[Q]: Ella waves good-bye from the bus. What body system pulls on bones to let Ella wave her arm?  
 (A) muscular system (B) nervous system (C) digestive system (D) circulatory system
[A]: A


[Q]: Soda water is a liquid that has bubbles of carbon dioxide in it. Which term best describes soda water?  
 (A) a mixture (B) a molecule (C) an element (D) a compound
[A]:
A