You sight another power-driven vessel dead ahead showing both the red and green sidelights. Which action are you required to take?

Answer: C — Alter your course to starboard

When you encounter another power-driven vessel directly ahead that is displaying both red and green sidelights, this indicates that the vessel is either not on a proper course or is being operated improperly. According to the Rules of the Road, when you see red and green sidelights of another power-driven vessel directly ahead, you must take action to avoid a collision. The appropriate maneuver in this scenario is to alter your course to starboard. By doing so, you create a safe passage, allowing both vessels to navigate without the risk of collision. This action aligns with Rule 14, which emphasizes that vessels should take action to avoid collisions by adjusting their course and speed. Maintaining your course or altering to port would not provide a clear and safe path in this situation, as it could result in a dangerous overlap of navigation patterns. Reducing speed alone might not be sufficient to avoid a potential collision, especially if the situation requires immediate action. Therefore, altering your course to starboard is the correct and safest response in this circumstance.