BOTH INTERNATIONAL & INLAND A power-driven vessel towing another vessel astern (tow less than 200 meters) shall show __________.

Correct Answer: Option B — two masthead lights in a vertical line instead of either the forward or after masthead lights

Under Rule 24(a), when the length of the tow exceeds 200 meters, three masthead lights in a vertical line are displayed at night, and a black diamond shape is shown by day.