Which sailboat is exhibiting the proper navigation light configuration?

The correct answer showcases the proper navigation light configuration for a sailboat, which is essential for safe operation at night or in low visibility conditions. A sailboat must have a red light on the port (left) side and a green light on the starboard (right) side at the front, indicating its orientation to other vessels. Additionally, a white light at the back serves as the stern light, allowing others to determine the boat's direction and position.

This traditional color coding helps mariners quickly identify the type of vessel and its direction of travel—red on the left and green on the right—as per maritime navigation rules. The presence of a white stern light also ensures that a vessel is visible from behind, creating a clear indication of its presence to approaching boats from that angle.

Other options do not conform to the established guidelines. For instance, having two green lights or a red light at the back does not follow the standard for sailing vessels, and a single white light, while visible from all angles, fails to provide directional information pertinent to collision avoidance.