* Conduction is the transfer of heat through direct contact between substances. Heat energy is transferred from a warmer object to a cooler object when their molecules collide.

Let's break down why the other options are incorrect:

* A cold object heated with hot air: This is primarily an example of convection, where heat is transferred through the movement of fluids (like air).

* The Sun: The Sun's heat reaches Earth primarily through radiation, where energy is transferred through electromagnetic waves.

In summary: Conduction requires direct physical contact between objects for heat transfer to occur.