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: Pathology
[{'content': "The main causative agent of Ludwig's angina is: \nSelect and explain. \nA. Anaerobic streptococci, B. Aerobic streptococci, C. Staphylococci, D. Legionella infection", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]