What is the function of the device labeled "3" shown in the illustration? Illustration MO-0111

Correct Answer: Option B — The cooler removes sensible heat from the jacket water.

Device '3' is the jacket water cooler, which functions as a heat exchanger. It removes sensible heat from the engine's fresh water cooling system by transferring it to the sea water circuit. This maintains the engine at its optimal operating temperature, preventing overheating and ensuring proper thermal expansion of engine components.