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: Radiology
[{'content': 'In atresia of cardiac end of stomach, X-ray chest is best done with: \nSelect and explain. \nA. Conray 240, B. Urograffin, C. Barium sulphate, D. Dianosil', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Dianosil', 'role': 'assistant'}]