Which choice correctly describes what happens during heating?
1. some of the energy in the system with more thermal energy will go into the system with less thermal energy, regardless of the temperatures of the systems.
2. some of the energy in the system with less thermal energy will go into the system with more thermal energy, regardless of the temperatures of the systems.
3.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.
4. 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.

Option 4

Explanation:

During heating actually heat transfer takes place from a body at higher temperature to a body at lower temperature and the heat transfer takes place until both attain the same temperature  

Therefore heat transfer depends on the temperature of the systems

Now while comparing the thermal energies of the systems, if both the systems have same mass then the system which is at higher temperature has greater thermal energy when compared to the system which is at lower temperature

So in this case assuming that both the systems have same mass then the energy will leave the system with greater thermal energy and go into the system with less thermal energy as the system with greater thermal energy in this case will be at higher temperature and we are considering this assumption because thermal energy not only depends on temperature but also depends on mass of the system