Final answer:
The nurse caring for a child with Duchenne's muscular dystrophy would document progressive muscle weakness, primarily affecting the legs and pelvis.
Step-by-step explanation:
The nurse caring for a child with Duchenne's muscular dystrophy would document progressive muscle weakness, primarily affecting the legs and pelvis. Duchenne muscular dystrophy is a genetic disorder that causes a lack of the protein dystrophin in muscle cells, leading to muscle fiber degradation and loss of muscle mass over time. This results in increasing functional impairments and weakness in the affected muscles.