What is the treatment of choice for a child with intussusception?

A. A barium enema: A barium enema is both diagnostic and therapeutic for intussusception in many cases. It helps to diagnose the condition by visualizing the telescoped intestine and can also often reduce the intussusception by hydrostatic pressure. B. IV fluids until the spasms subside: IV fluids are important for managing dehydration and maintaining hydration but do not directly treat intussusception. C. Immediate surgery: Surgery may be necessary if non-operative reduction methods fail or if there are complications like bowel necrosis or perforation. However, it is not the first-line treatment choice. D. Gastric lavage: Gastric lavage (stomach pumping) is not indicated for the treatment of intussusception.