The correct answer is B) preventing further movement of the bone. For a simple fracture, the first priority is to immobilize the affected area and prevent further damage to the injured limb. Attempting to set the fracture or apply a tourniquet could potentially worsen the injury. Alternately applying hot and cold compresses is not the appropriate first-aid treatment for a fracture. The goal is to stabilize the limb and minimize movement to avoid causing additional harm until the individual can receive proper medical attention.