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': "Which is not true of Ludwig's angina? \nSelect and explain. \nA. Usually arises from an infected molar, B. Involves submandibular space., C. May need emergency tracheostomy, D. None of the above", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]