What happens to heat when it flows from a hotter object to a colder object?

When heat flows from a hotter object to a colder object, the thermal energy of the hotter object decreases while that of the colder object increases. This transfer of heat, driven by the temperature difference, continues until thermal equilibrium is reached, meaning both objects attain the same temperature.

The net effect of this process is a decrease in the thermal energy of the hotter object (or a decrease in heat content) while the colder object absorbs that energy, resulting in an increase in its thermal energy. Therefore, the correct choice indicates that the heat content decreases as it flows from the hot to the cold object, aligning with the second law of thermodynamics, which states that heat spontaneously flows from higher to lower temperatures in an isolated system.