What does the term 'air shares' refer to in cavern diving?

The term 'air shares' in cavern diving specifically refers to the practice of sharing air during emergencies. This situation can arise if a diver experiences an equipment malfunction, runs low on gas, or if they need to assist a buddy in distress. In such critical instances, the ability to share air can be paramount for safety, as it allows both divers to maintain breathing air while ascending or exiting the dive environment. This practice is an essential skill in diving training, emphasizing the importance of buddy communication and proactive emergency preparedness.

The other options, while related to diving concepts, do not accurately capture the specific meaning of 'air shares' as it pertains to emergencies in cavern diving.