What must be true about two objects if heat is flowing between them?

The objects must be different temperatures.
The objects must be the same temperature.
The objects must both be over room temperature.
The objects must both be under room temperatu

The objects must be different temperatures.

Explanation:

For heat to flow between two objects, heat must be flowing between them. The thermal gradient allows for the flow of heat. Heat is a form of energy that is dissipated from one place to another based on temperature difference.

Temperature is the degree of hotness or coldness of body. It is power by heat energy between two bodies.

Heat generally flows from a body at high temperature to one at low temperature. When thermal equilibrium is established and both bodies have the same temperature, heat will stop to flow.