Explanation
Answer: d. CPAP mask
Explanation: A CPAP mask is the most appropriate oxygen delivery system for a client with sleep apnea who requires positive pressure ventilation. It delivers a continuous flow of air or oxygen at a constant pressure to keep the airway open during sleep.
Incorrect choices:
a. Nasal cannula does not provide positive pressure ventilation and is not suitable for addressing sleep apnea.
b. Venturi mask and c. Non-rebreather mask are not designed to deliver positive pressure ventilation and are not commonly used for sleep apnea management.