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': 'Color changes seen in ANUG may \nSelect and explain. \nA. Marginal, B. Diffuse, C. Patch-like, D. Lace-Like', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]