BOTH INTERNATIONAL & INLAND At night you sight a vessel displaying a single green light. This is a __________.

Correct Answer: Option A — sailing vessel

Pursuant to COLREGS Rule 25(c), a sailing vessel under way may, in addition to sidelights and a stern light, exhibit at or near the top of the mast two all-round lights in a vertical line, the upper red and lower green, but a single green light alone does not conform to navigation light standards except when viewed as part of a combination tricolor sector.