BOTH INTERNATIONAL & INLAND In illustration D023RR below item "A" represents the arc of visibility of which of the following lights?

Correct Answer: Option C — red sidelight

Rule 21(b) defines sidelights as showing an unbroken arc of 112.5 degrees from right ahead to 22.5 degrees abaft the beam. In standard marine navigation diagrams, item "A" on the port side represents the red sidelight's sector of visibility.