The correct answer is D) All of the above. The vessel bridge-to-bridge radiotelephone regulations apply to the following vessels while navigating: 1) Power-driven vessels 20 meters in length or greater 2) Towing vessels 26 feet in length or greater 3) Passenger vessels of 100 gross tons or greater, carrying one or more passengers for hire These regulations require the vessels to maintain a continuous listening watch on the designated bridge-to-bridge radiotelephone channel, and to use the radio to communicate vital navigational information with other vessels in the vicinity. The regulations help to enhance navigational safety by facilitating communication between vessels. The other answer choices are incorrect because they only list a subset of the vessels required to comply with these regulations.