Question 723 Rules of the Road

The correct answer is C) green sidelight. In the illustration D023RR, the arc of visibility represented by "B" corresponds to the green sidelight, which is required to be visible from the bow to 112.5 degrees abaft the beam (side) on the starboard side of the vessel, as per the International Regulations for Preventing Collisions at Sea (COLREGS). The other options are incorrect because the stern light (A) has a different arc of visibility, the red sidelight (B) is on the port side, and the yellow flashing light (D) is not a standard navigation light required by the COLREGS.