INTERNATIONAL ONLY In addition to her running lights, a vessel constrained by her draft while underway shall carry which lights in a vertical line?

Correct Answer: Option D — Three red lights

Under COLREGS Rule 28, a vessel constrained by her draft must display three red lights in a vertical line in addition to the lights prescribed for power-driven vessels in Rule 23. This vertical arrangement serves as a clear visual warning of the vessel's limited maneuverability due to depth.