What is a forced warm air system designed to utilize for heating?

A forced warm air system is specifically designed to use a furnace that is equipped with a fan or blower. This system operates by heating air in the furnace and then distributing that warm air throughout the building via ductwork. The fan or blower is crucial because it ensures that the heated air circulates effectively, providing consistent warmth in various rooms.

The other options each pertain to different heating or cooling technologies. A geothermal heat pump utilizes the earth's stable temperature to heat and cool a building but does not rely on forced air. A central air conditioning unit is primarily used for cooling, not heating, and thus would not fit the context of a heating system. An electric radiator heats space through conduction and radiation, not through forced air distribution, making it distinctly different from a forced warm air system.