Question 372Navigation General

The correct answer is C) shows a light that changes color. An alternating light is a navigation light that alternates between two different colors, typically red and green. This type of light is used to mark the center of a navigable channel or to indicate the preferred route for vessels. The alternating color change helps to distinguish this type of light from a fixed-color light, which would not change color. The other answer choices are incorrect because they do not accurately describe the defining characteristic of an alternating light, which is the change in color. Option A describes a light marking a lesser-used channel, option B describes a light with varying length of illumination, and option D describes a light used as a replacement, none of which are accurate for an alternating light.