How should vessels position their lights according to collision regulations?

Vessels must position their lights according to specific arrangements outlined in collision regulations to ensure safe navigation and effective communication at sea. The correct option emphasizes that the arrangement of forward lights, sidelights, and stern lights is detailed in the International Regulations for Preventing Collisions at Sea (COLREGS).

Each type of vessel is required to have specific lights that are placed according to their position on the vessel to provide clear information about the vessel's presence, direction, and status to others. For instance, sailing vessels must display sidelights and a stern light, while power-driven vessels have a different arrangement that includes a masthead light. These arrangements help others determine the type of vessel and the direction it is moving, which is crucial for preventing collisions.

In terms of other choices, while the color and intensity of lights must correspond to the vessel's type, this option does not address the arrangement itself, which is critical for visibility and compliance with maritime safety regulations. Additionally, requiring only one light source based on the vessel's length is too simplistic and does not reflect the comprehensive regulations that dictate multiple light placements to convey the necessary information. Overall, the specific arrangement of lights helps ensure safe navigation by providing essential visual cues to nearby vessels.