Final answer:
The correct position for a client with pneumonia to promote postural drainage is the Fowler's position, where the patient is semi-upright.
Step-by-step explanation:
A nurse caring for a client with pneumonia should position the client in a way that promotes postural drainage. While lying supine is face-up and prone is face-down, neither are optimal for postural drainage in pneumonia.
The Fowler's position, where the patient is seated in a semi-upright sitting position (typically at 45 to 60 degrees), is most beneficial for this purpose. It facilitates breathing by reducing the pressure on the diaphragm and allows for better expansion of the chest.
Therefore, the correct answer is C. Fowler's position.