Which lights should be exhibited by a sailing vessel?

A sailing vessel should exhibit side lights and a stern light when under sail. This configuration is essential for visibility and safety at sea, as it helps other vessels identify the sailing vessel’s direction and activity. The side lights, typically green on the starboard side and red on the port side, allow other vessels to determine which direction the sailing vessel is heading. The stern light, which is white, helps indicate the vessel’s position from behind.

This setup ensures compliance with the COLREGs, which outline the required navigation lights for different types of vessels, enhancing overall navigational safety. In contrast, the other answer choices describe configurations that are either incomplete for a sailing vessel's requirements or pertain to other types of vessels.