BOTH INTERNATIONAL & INLAND A 30-meter tug is underway and NOT towing. At night, this vessel must show sidelights and which additional light(s)?

Correct Answer: Option B — one masthead light and a stern light

Rule 23(a) mandates that a power-driven vessel underway must exhibit a masthead light forward, sidelights, and a stern light. For a vessel under 50 meters in length, only one masthead light is required, positioned forward of the amidships section to ensure proper visibility and identification.