BOTH INTERNATIONAL & INLAND Vessel "A" is overtaking vessel "B" as shown in illustration D017RR below. Which color light will vessel "A" observe on vessel "B"?

Correct Answer: Option D — White

Rule 13 defines an overtaking situation as coming up from a direction more than 22.5 degrees abaft the beam. In this position, the overtaking vessel can only see the stern light of the vessel being overtaken. Rule 21(c) specifies that the stern light is a white light.