BOTH INTERNATIONAL & INLAND Your vessel is underway in fog and you hear one prolonged and three short blasts. Which vessel would this signal indicate?

Correct Answer: Option B — A vessel being towed

Rule 35(c) specifies that a vessel being towed, or the last vessel of a tow if manned, must sound one prolonged blast followed by three short blasts at intervals of not more than two minutes. This signal serves to warn other vessels of the presence of the towed object.