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': 'Continuous diaphragm sign is seen in \nSelect and explain. \nA. Pneumo mediastinium, B. Pseudo pneumomediastrinium, C. Pleural effusion, D. Pulmonary infarct', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Air collects beneath the pericardium so the central part of diaphragm become visible represents pneumo mediastinium.', 'role': 'assistant'}]