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: Forensic Medicine
[{'content': 'Buonian line is seen due to the exposure of? \nSelect and explain. \nA. Arsenic, B. Silicon, C. Mercury, D. Lead', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A stippled blue line called Buonian line is seen on the gums in 50-70% of cases of lead poisoning.It appears due to the subepithelial deposits of granules at the junction with teeth, only near diy or carious teeth, within a week of exposure, especially on upper jaw. It is due to the formation of lead sulphide by the action of hydrogen sulphide formed by the decomposition of tooth. Ref: The Essentials of Forensic Medicine and Toxicology 29th Ed Page 488.', 'role': 'assistant'}]