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: Surgery
[{'content': 'Odontogenic infections are mostly caused by \nSelect and explain. \nA. MIXED bacteria, B. Anaerobic bacteria, C. Aerobic bacteria, D. Streptococci', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]