INTERNATIONAL ONLY In which case would an overtaking vessel sound a whistle signal of two prolonged followed by one short blast?

Correct Answer: Option D — When overtaking in a narrow channel

Rule 9(e)(i) requires a vessel intending to overtake in a narrow channel to sound two prolonged blasts followed by one short blast to indicate an intention to overtake on the starboard side. This specific signal is unique to narrow channel operations under the International Rules of the Road.