Which type of light is visible from any direction on a boat?

The reason the all-around white light is the correct answer is that it is designed to be visible from any direction, providing 360 degrees of illumination around the vessel. This type of light is particularly important for boats operating at night or in low visibility conditions, as it signals the presence of the vessel to other boaters from all angles.

In contrast, red and green lights are specifically used as sidelights, indicating a boat's port (left) and starboard (right) sides, respectively. These lights are only visible from the front of the boat and are not meant to signal to vessels approaching from behind. Sidelights therefore do not serve the purpose of indicating the vessel's presence from all directions, further reinforcing why the all-around white light is essential for safety on the water.