Question 1527Navigation General

You are correct that the answer is A) prime vertical. The prime vertical is the great circle of the celestial sphere that passes through the zenith, nadir, and the eastern and western points of the horizon. This is because the prime vertical is defined as the vertical circle that is perpendicular to the celestial meridian, which passes through the north and south points of the horizon. The other options are incorrect because: B) hour circle is the great circle that passes through the celestial poles. C) principal vertical is not a standard term in navigation. D) celestial meridian is the great circle that passes through the north and south points of the horizon and the zenith and nadir.