This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'All are true about intussusception except \nSelect and explain. \nA. Barium must be used in children after 48 hours, B. X-ray shows paucity of colonic gas, C. USG shows pseudoxidney sign, D. X-ray shows lump shadow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]