Air cooled engines dissipate heat through:

Air-cooled engines rely on a system where the heat generated during combustion is dissipated directly to the surrounding air. The cooling fins on the cylinder and the cylinder head increase the surface area available for heat transfer, allowing more efficient dissipation of heat. As air flows over these fins, it absorbs heat from the engine components and carries it away, effectively cooling the engine. This method is simple and effective for many small and general aviation aircraft engines that operate in relatively open and unobstructed airflows.

The other options refer to cooling methods used in different types of engines. The radiator fins mentioned would be applicable to liquid-cooled engines, where coolant circulates through a radiator to exchange heat with the air. A cylinder head temperature probe is a tool for monitoring temperature but doesn’t facilitate cooling itself. A closed-loop cooling system involves a coolant circulating between components to regulate temperature, which is not relevant for air-cooled designs.