What must tenders do during the terminal portion of treatment in the chamber?

During the terminal portion of treatment in the chamber, it is essential for tenders to breathe oxygen. This is a crucial part of hyperbaric oxygen therapy, which is used to treat various conditions, including decompression sickness. During this stage, the patient is exposed to high levels of oxygen in a controlled environment, which helps reduce nitrogen bubbles and facilitate the healing of damaged tissues.

Breathing oxygen during this phase ensures that the body can efficiently eliminate excess nitrogen, enhance oxygen delivery to tissues, and support cellular metabolism. This is particularly important as the body adjusts to atmospheric pressure changes, and administering pure oxygen can significantly aid in the recovery process.

In contrast, other options like breathing regular air or exiting the chamber would not provide the necessary therapeutic benefits associated with the treatment, while increasing dive depth does not apply in the context of the recovery and treatment protocols being followed. Understanding the purpose of breathing oxygen during this phase highlights its critical role in therapeutic effectiveness for the diver's safety and recovery.