Which of the following describes a sailing vessel?

A sailing vessel is defined as a boat or ship that is propelled primarily by sails, relying on the wind for movement rather than mechanical power. This definition encompasses any vessel that operates under sail alone, making it distinct from vessels that use engines or oars.

The reason this choice is correct is that it emphasizes the primary propulsion method of the vessel. When a vessel is described as under sail only, it indicates that the sails are the sole means by which it is powered, thus fitting the definition of a sailing vessel.

In contrast, options that suggest the presence of engines or oars do not align with the traditional understanding of what constitutes a sailing vessel. A vessel that uses both sails and an engine, while it might be capable of sailing, falls into the category of a motor-sailer or hybrid vessel rather than being classified as purely a sailing vessel. Similarly, vessels that rely solely on oars or motors lack the essential characteristic of being a sailing vessel, which is the primary dependence on sails for movement through the water.