INTERNATIONAL ONLY A power-driven vessel pushing ahead or towing alongside will show sidelights, a stern light, and which additional light(s)?

Correct Answer: Option B — Two masthead lights in a vertical line

COLREG Rule 24(a)(i) mandates that a power-driven vessel pushing ahead or towing alongside must display two masthead lights in a vertical line. These lights, in addition to the standard sidelights and stern light, provide clear indication of the vessel's status as a towing unit.