Which choice correctly describes what happens during cooling?

The thermal energy found in each system remains the same, but heat is transferred into the system with the lesser thermal energy.
Thermal energy moves from one system into the other until the amount of energy in the two systems is reversed.
If two systems are at different temperatures, energy will leave the system with less thermal energy and go into the system with greater thermal energy.
If two systems are at different temperatures, energy will leave the system with greater thermal energy and go into the system with less thermal energy.