What function does the water pump serve in a vehicle's cooling system?

The water pump plays a critical role in a vehicle's cooling system by circulating the coolant, which is essential for maintaining the engine's optimal operating temperature. It moves the coolant from the engine to the radiator and back again, allowing for the removal of heat generated by the engine during combustion. This continuous circulation ensures that the engine does not overheat and operates efficiently.

When the engine generates heat, the coolant absorbs this heat as it passes through the engine block, then the water pump directs the heated coolant to the radiator where it releases the heat into the air. This process is vital for preventing engine damage and ensuring longevity and performance. The water pump's ability to maintain a consistent coolant flow allows for effective temperature regulation, which is why controlling coolant flow is the correct function described in the question.