130. 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?

A vessel being towed, if manned, uses a distinct fog signal (one prolonged followed by three short blasts) according to Rule 35, unlike vessels not under command, fishing with trawls, towing astern, which all use one prolonged followed by two short blasts.