BOTH INTERNATIONAL & INLAND A sailing vessel is NOT allowed to show the all- round red over green lights on the mast if __________.

Correct Answer: Option A — her sidelights and stern light are combined in one lantern and shown on the mast

COLREGS Rule 25(c) allows a sailing vessel to exhibit optional all-round red over green lights at the masthead, but expressly prohibits their use when a combined tricolor or combined sidelight and stern light lantern is fitted.