Which of the following is the most important nursing intervention for a patient with pneumonia experiencing difficulty breathing?

Rationale: A. Administering antibiotics is essential for treating the infection, but it does not provide immediate relief from hypoxia or respiratory distress. B. Chest physiotherapy can help mobilize secretions, but it is supportive and not the priority when the patient is experiencing acute breathing difficulty. C. Encouraging fluid intake helps thin secretions but does not address immediate oxygenation needs. D. Administering supplemental oxygen is the priority intervention because it directly improves oxygenation and alleviates hypoxemia, which is critical in a patient with pneumonia experiencing difficulty breathing.