This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 1, Subject name: Forensic Medicine
[{'content': 'Xanthoproteic reaction is due to the formation of \nSelect and explain. \nA. Trinitrophenol, B. Mononitrophenol, C. Nitric acid, D. Pyrocathechol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Nitric acid is a powerful oxidising agent and reacts with organic matter to produce trinitrophenol, liberating nitrogen monoxide (xanthoproteic reaction).', 'role': 'assistant'}]