A nurse is caring for a school-age child following the application of a cast to a fractured right tibia. Which of the following actions should the nurse take first?

The correct answer is D: Elevate the child's leg first. Elevating the child's leg helps reduce swelling and pain by promoting venous return and decreasing pressure on the injured area. This immediate action is crucial to prevent complications such as compartment syndrome. Teaching the child about cast care (A) is important but can wait until after addressing the immediate physical needs. Petaling the edges of the cast (B) may be necessary later to prevent skin irritation, but it is not the priority at this moment. Administering pain medication (C) is important for comfort but should come after elevating the leg.