BOTH INTERNATIONAL & INLAND A vessel signals you three flashes on its maneuvering light. What is the meaning of this signal?

Correct Answer: Option B — "I am operating astern propulsion"

Rule 34(b) states that when vessels are in sight of one another, a vessel operating astern propulsion shall indicate this by sounding three short blasts. This may be supplemented by an appropriate light signal of three flashes, which carries the exact same meaning as the audible whistle signal.