A nurse is caring for a client who has pneumonia. The client's oxygen saturation is 85%. Which of the following actions should the nurse take first?

A. Humidification can help loosen secretions and improve comfort, but it does not immediately address hypoxemia. While useful as a supportive measure, it is not the first priority when oxygen saturation is critically low. B. Elevating the head of the bed promotes lung expansion, improves diaphragmatic movement, and enhances ventilation-perfusion matching, which can help increase oxygen saturation quickly. In a client with pneumonia and hypoxemia (SpO2 85%), improving oxygenation is the immediate priority, and raising the head of the bed is a rapid, non-invasive intervention that supports this goal. C. Incentive spirometry encourages deep breathing and helps prevent atelectasis, but it requires patient cooperation and time to improve oxygenation. It is not the fastest method to address acute hypoxemia. D. Fluids can help thin secretions and improve mucus clearance over time, but they do not have an immediate effect on oxygen saturation. This is a supportive measure, not a first-line intervention for low SpO2.