BOTH INTERNATIONAL & INLAND While underway in a fog, you hear a whistle signal of one prolonged blast followed by two short blasts. This signal could be sounded by all of the following EXCEPT which vessel?

Correct Answer: Option D — Being towed

Rule 35(c) requires vessels not under command, restricted in ability to maneuver, fishing, or towing to sound one prolonged followed by two short blasts. A vessel being towed is not included in this category, as it is required to sound one prolonged followed by three short blasts instead.