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]: Melting, boiling, and freezing are examples of  
 (A) physical changes. (B) chemical changes. (C) magnetic changes. (D) electrical changes.
[A]: A


[Q]: In an accurate diagram of the solar system, which object would be shown closest to Earth?  
 (A) the Moon (B) the asteroid belt (C) Mars (D) Saturn
[A]: A


[Q]: From smallest to largest, the levels of organization in living things are  
 (A) tissues, cells, organs, organ systems. (B) tissues, cells, organ systems, organs. (C) cells, tissues, organs, organ systems. (D) cells, tissues, organ systems, organs.
[A]:
C