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: Dental
[{'content': "Punched-out, crater-like depressions at the crest of the gingiva, covered by gray pseudo- membranous slough, which is demarcated from the remainder of the gingiva by linear erythema, are characteristic of \nSelect and explain. \nA. Desquamative gingivitis, B. Erythema multiforme, C. Lichen planus, D. Vincent's stomatitis", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]