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: Medicine
[{'content': 'Most common cause of lung abscess \nSelect and explain. \nA. Staph aureus, B. Oral anaerobes, C. Klebsiella, D. Tuberculosis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Oral Anaerobes According to Harrison Most nonspecific lung abscesses are presumed to be due to anaerobic bacteria.", 'role': 'assistant'}]