BOTH INTERNATIONAL & INLAND Which vessel MUST show two masthead lights in a vertical line?

Correct Answer: Option B — A power-driven vessel less than 50 meters in length with a 20-meter tow

Under Inland Navigation Rules, for the condition where 'Which vessel MUST show two masthead lights in a vertical line', the correct requirement is: 'A power-driven vessel less than 50 meters in length with a 20-meter tow'. This standard ensures clear navigational intent and collision avoidance.