This is a poor question, both a 50M vessel with a tow less than 200M and a towing vessel less than 50M towing greater than 200M show the same lights. Also the question places the word "forward" in the title indicating that the vessel has 2 masts.
Deck
Rules of the Road: BOTH INTERNATIONAL & INLAND A vessel towing is showing three forward white masth...
Discussing this exam question.