The correct answer is D) stuffing box. A stuffing box is a device used where a propeller shaft passes through the hull of a vessel. It is designed to prevent water from entering the vessel through the opening where the propeller shaft penetrates the hull. The stuffing box contains a series of packing materials that form a watertight seal around the rotating shaft, allowing it to pass through the hull without leaking. The other answer choices are incorrect because: A) a sea cock is a valve used to control the flow of water through a hull opening, not specifically for the propeller shaft; B) a propeller boss is the central part of the propeller that attaches to the shaft; and C) a stop-water is not a standard term used to describe the device used to seal the propeller shaft.