Which part below keeps the engine from overheating?

The water pump plays a crucial role in maintaining the engine's temperature by circulating coolant throughout the cooling system. This process helps to absorb heat from the engine and dissipate it through the radiator, preventing the engine from overheating. The water pump ensures that the coolant flows efficiently between the engine block, radiator, and other components, maintaining a consistent temperature range that is essential for optimal engine performance.

In contrast, the other parts mentioned do not serve the primary function of cooling the engine. The air cleaner is responsible for filtering dirt and debris from the air entering the engine, the condenser is mainly involved in the air conditioning system, and the heater core functions as a mini-radiator to provide heat for the cabin but does not contribute to cooling the engine. Thus, the water pump is the key component that prevents engine overheating by ensuring proper coolant circulation.