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': 'Bismuth intoxication is manifested as \nSelect and explain. \nA. pigmentation in areas of inflammation, B. Burtonian line, C. Gingiva, D. Blackish line in the mucosa', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]