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]: A scanning electron microscope is best suited for observing  
 (A) diffraction of light. (B) tectonic features on planets. (C) the surfaces of small objects. (D) topographical features on the ocean floor.
[A]: C


[Q]: Which organ is the site of gas exchange between the body and the environment?  
 (A) spleen (B) liver (C) lungs (D) pancreas
[A]: C


[Q]: Energy is transferred in an electrical circuit through  
 (A) static protons. (B) moving protons. (C) static electrons. (D) moving electrons.
[A]:
D