Temperature refers to the a. amount of heat energy in an object b. arrangement of the atoms in matter c. average kinetic energy of the particles in a substance d. pressure exerted by atoms on anything that touches them

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.