BOTH INTERNATIONAL & INLAND The stern light shall be positioned such that it will show from dead astern to how many degrees on each side of the stern of the vessel?

Correct Answer: Option C — 67.5°

Rule 21(c) defines a sternlight as a white light showing over an unbroken arc of the horizon of 135 degrees. It must be positioned to project this light 67.5 degrees from dead astern to both the port and starboard sides of the vessel.