Final answer:
The protective supine position is lying on one's back, which helps prevent pneumonia by keeping airways clear and reducing the risk of infection.
Step-by-step explanation:
The protective supine (dorsal recumbent) position is lying flat on the back, which corresponds with option B from the question. This position is used during medical recovery and some surgical procedures to promote safety and prevent complications. In this context, lying in the supine position can help prevent pneumonia, which is a potential concern for patients who are immobile or bedridden for extended periods. Pneumonia can occur when there's a buildup of secretions in the lungs, and being in a supine position helps to keep airways clear and reduce the risk of these secretions leading to an infection.