While receiving a transfusion of packed red blood cells, a school-aged child begins to experience itchy skin, hiver a tonsillectomy. What should the nurse do first for this child?

The correct answer is B: Stop the transfusion. Itchy skin and hives are symptoms of a transfusion reaction, which can be indicative of an allergic reaction or hemolytic reaction. The first priority is to stop the transfusion to prevent further complications and assess the child's condition. Obtaining a blood culture (choice A) would not address the immediate need to stop the transfusion. Slowing the transfusion rate (choice C) may not be sufficient to address the reaction already occurring. Providing a diuretic (choice D) is not indicated in this situation.