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': 'The causes of homogenous opacity on X-ray is all except: \nSelect and explain. \nA. Pleural effusion, B. Diaphragmatic hernia, C. Massive consolidation, D. Emphysema', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Emphysema', 'role': 'assistant'}]