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': 'ANUG is best visualized \nSelect and explain. \nA. Crater like lesions, B. Severe gingivitis, C. Recession of gingiva, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]