A nurse is preparing a child for a lumbar puncture. In which of the following positions should the child be placed for the procedure?

The correct answer is B: Lateral. Placing the child in the lateral position for a lumbar puncture allows for better visualization of the spinal landmarks and facilitates easier access to the lumbar region for the procedure. This position also helps minimize the risk of complications such as nerve injury or leakage of cerebrospinal fluid. Other positions are incorrect: A: Prone would not provide the optimal access needed for a lumbar puncture. C: Supine does not allow for proper alignment of the spine. D: Semi-Fowler's position would not provide the necessary exposure of the lumbar region.