A power-driven vessel of less than 12 meters may use an all-around white light to serve as what?

A power-driven vessel of less than 12 meters may use an all-around white light as both a mast light and a stern light. This is in accordance with the International Regulations for Preventing Collisions at Sea (COLREGs), which allow vessels of this size to combine the functions of navigation lights for simplicity and efficiency.

For these smaller vessels, the all-around white light provides visibility from all angles, serving the dual purpose of being a mast light when underway and a stern light when at anchor. This simplifies the light configuration without compromising safety, allowing operators of smaller vessels to comply with navigation regulations effectively. The other options mention combinations of different lights that either do not meet the requirements or suggest an incorrect role for the all-around white light.