The correct answer to this question is letter A which is visualizing. Visualizing is the act of picturing a certain situation in your head to recall how it works. In this example, you want to remember how a volcano functions. A volcano erupts. So in order to remember this, you picture in your mind a volcano that is erupting. So once you are asked a question about the functions of a volcano, your mind will immediately show the picture of a volcano erupting.
