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]: 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.
[EX A]: B

[EX Q]: Which of the following forms of energy is released or absorbed in most chemical reactions?      
 (A) light energy (B) electrical energy (C) sound energy (D) heat energy
[EX A]: D

[EX Q]: The best example of heat transfer by convection is when  
 (A) sunlight warms soil. (B) a ceiling fan blows air. (C) flames heat up a pan. (D) heat rises in a chimney.
[EX A]:
D