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': 'Most important cause of bulging fissure \nSelect and explain. \nA. Klebsiella pneumonia, B. Legionella pneumonia, C. Mycobacterium tuberculosis, D. Staph aureus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: All the above are causes of bulging fissure.\nMost important cause is Klebsiella pneumonia.', 'role': 'assistant'}]