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: ENT
[{'content': "All of the following cause a gray-white membrane on the tonsils, except: \nSelect and explain. \nA. Infectious mononucleosis, B. Ludwig's angina, C. Streptococcal tonsillitis, D. Diphtheria", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ludwigs angina is cellulitis of submandibular space. It does not lead to membrane formation over tonsils.', 'role': 'assistant'}]