What additional feature might a buoy possess to assist nighttime navigation?

A buoy equipped with radar reflectors or lights plays a vital role in assisting nighttime navigation. The use of lights is particularly important because it allows mariners to visually identify the buoy and its significance in the dark. Lights can be designed to flash or remain steady, providing crucial information about the buoy's position, type, and status. Radar reflectors enhance the buoy's visibility on radar systems, enabling vessels to detect them even when they are not visible to the naked eye. These features collectively increase safety by helping navigators avoid hazards during low visibility conditions or at night, ensuring they can maintain a safe course.

Other options like sound signals or flashing patterns alone lack the complete navigational assistance necessary for a vessel to navigate effectively at night. Bright colors during the day might be helpful for daytime recognition, but they do not provide the necessary guidance after dark when visual cues are diminished. Hence, the combination of radar reflectors and lights is essential for optimal nighttime navigation safety.