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]: Sharpening a pencil and tearing paper are examples of physical changes. Which statement describes why these are physical changes?  
 (A) There is a change in how the objects are used. (B) There is a change in the appearance of the objects. (C) There is a change in the materials from which the objects are made. (D) There is a change in both the appearance of the objects and the materials from which they are made.
[A]: B


[Q]: Which of the following is the best example of potential energy?  
 (A) a fallen rock (B) a burning match (C) a liter of gasoline (D) a red-hot piece of iron
[A]: C


[Q]: A water company uses lab tests on the water supply before sending the water through pipes to people's homes. How do these lab tests help people?  
 (A) by adding minerals and nutrients to the water (B) by checking the water to make sure it is safe to drink (C) by filtering chemicals and organisms out of the water (D) by stopping harmful substances from entering the water
[A]:
B