Which of the following describes the correct use of a backup light during night diving?

Using a backup light during night diving is fundamentally about safety and preparedness. The primary purpose of a backup light is to serve as an alternative illumination source if the primary light fails. This is crucial because, without adequate lighting at night, visibility can be severely limited, potentially leading to dangerous situations, such as disorientation or difficulties in communicating with dive buddies.

In practice, divers carry a backup light for this very reason: to ensure that they remain safe and have the ability to navigate and signal to each other if their main source of light goes out. By having this redundancy, divers can extend their safety net under low visibility conditions.

Other choices, while they may seem reasonable, do not align with the core objective of carrying a backup light. Signaling non-divers, illuminating dive equipment, or attracting marine life are not primary functions of a backup light and can be accomplished through other means or tools suitable for their respective tasks. Having a reliable source of light is essential for night dives, making the role of a backup light critical in maintaining safety and facilitating clear communication under challenging conditions.