Heat that flows by conduction is the transfer of thermal energy between substances in contact. What must occur for this to happen?

Conduction transfers thermal energy when substances are in contact and there is a temperature difference between them. The particles in the warmer system have greater average kinetic energy, so energy flows toward the cooler system. Thus, the choice saying one system has higher kinetic energy is correct; if they were the same temperature, there would be no net heat transfer.

AI-written and checked against the verified answer.