BOTH INTERNATIONAL & INLAND In illustration D023RR below item "C" shows the arc of visibility of which of the following?

Correct Answer: Option D — None of the above

Rule 21(c) defines a sternlight as a white light showing over an unbroken arc of the horizon of 135 degrees. Since item C represents this 135-degree sternlight sector, none of the listed options (sidelights or flashing yellow lights) are correct.