A nurse is caring for a child who has had a lumbar puncture. The nurse should monitor the child for which of the following complications?

The correct answer is D: Headache. After a lumbar puncture, the child may experience a post-dural puncture headache due to leakage of cerebrospinal fluid. This headache is typically aggravated by sitting or standing and relieved by lying down. Double vision (A) is not a typical complication. Nuchal rigidity when standing (B) is more indicative of meningitis. Pain in the posterior iliac crest (C) is not a common complication of lumbar puncture. Therefore, monitoring for headache (D) is crucial.