BOTH INTERNATIONAL & INLAND A vessel engaged in fishing while at anchor shall sound which fog signal?

Correct Answer: Option D — One prolonged and two short blasts at two minute intervals

Rule 35(c) requires a vessel engaged in fishing, whether underway or at anchor, to sound one prolonged blast followed by two short blasts at intervals of not more than two minutes. This identifies the vessel's restricted maneuverability status to other traffic navigating in restricted visibility conditions.