If the purpose was (A) to show how a volcano works, it would probably be shown in greater detail and from a clearer perspective. It the purpose was (B) to show the different parts of a volcano, than the image would not be so small or merely shown from the top. If the purpose was (D) to show the destructive power of a volcano, then it would likely show lava and its damage. Hence, the most probable answer is (C) to show a real-life example of a volcano.
