Question 1546Navigation General

The correct answer is A) Amplitude. The prime vertical is the reference point from which the angle of amplitude is measured. Amplitude is the angle between the prime vertical (an imaginary line running east-west) and the position of a celestial body at the time of its rising or setting. This angle is used to determine the azimuth, which is the horizontal direction of a celestial body from the observer's position. The other answer choices are incorrect because sextant angle refers to the angle measured by a sextant, azimuth is the horizontal direction of a celestial body, and local apparent noon is the time when the sun reaches its highest point in the sky.