Rules of the Road: BOTH INTERNATIONAL & INLAND At night, you see the lights shown in illustration D...

Under way not making way, no sidelights 🤓

Process of elimination...not two reds so not NUC. Wrong order (red-white-red) for RAM. Fishing underway is only red over white. So, pilot vessel, but why no sidelights? The only thing that fits is that you are seeing a pilot vessel from dead-astern, so the lower white light is the stern light.

Yes you are viewing from the stern so no running lights would be seen