BOTH INTERNATIONAL & INLAND A vessel at anchor shall display, between sunrise and sunset, on the forward part of the vessel where it can best be seen which shape?

Correct Answer: Option B — one black ball

Rule 30(a) specifies that a vessel at anchor shall exhibit one black ball in the forepart of the vessel where it can best be seen. This daylight signal is mandatory for all vessels at anchor to provide clear visual indication of their status to other vessels navigating in the area.