When selecting a buoyancy compensator (BC) for deep diving, you should ensure it has enough lift to:

The selection of a buoyancy compensator (BC) for deep diving is critical for ensuring safety and efficiency underwater. The correct answer emphasizes the importance of having a BC that possesses enough lift capability to bring another diver to the surface from depth. This capability is essential because, in an emergency situation, a diver may need assistance to safely ascend from depth.

In such scenarios, a BC with sufficient lift can help manage the added weight of the diver, equipment, and any potential additional gear, allowing for a controlled ascent that minimizes risks such as decompression sickness or barotrauma. This consideration is crucial in deep diving environments, where the challenges posed by pressure and buoyancy change necessitate reliable equipment.

The other choices, while relevant to some aspects of diving equipment selection, do not address the fundamental safety requirement during deep dives in the same way that the ability to assist another diver does. For example, accommodating heavy gear is important, but it does not directly tie into emergency scenarios that involve bringing a diver to the surface. Likewise, maintaining stability at the surface and fitting comfortably are significant for overall diving experience but do not reflect the critical life-saving function that a BC's lift capacity should provide in emergencies.