I believe A. is the answer. Temperature is the measure of heat, heat is considered to be the amount of vibration within an atom. Hot atoms will vibrate a lot, cooler atoms will no vibrate much. You can heat atoms up and cause them to break their bonds with other atoms and create liquids or gases. Hence, you can cool atoms and cause them to revert into a liquid from a gas, or solid from a liquid.
An aurora is a natural electric phenomenon that creates bright and colorful light displays in the sky. These dramatic and colorful lights are created when electrically charged particles from solar winds enter the Earth's atmosphere and interact with gases in the atmosphere.
