BOTH INTERNATIONAL & INLAND Under which conditions is a sailing vessel NOT allowed to show the all-round red over green lights on the mast?

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

Rule 25(c) states that a sailing vessel may exhibit red over green all-round lights at the masthead. However, this is prohibited if the vessel uses a combined lantern for sidelights and stern light, as the combined unit does not meet the specific separation requirements for the optional masthead signal.