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': "Which of the following poisoning is demonstrated by Kunkel's test? \nSelect and explain. \nA. Lead, B. CuSO4, C. CO, D. Dhatura", 'role': 'user'}, {'content': "Answer: C \nExplanation: Kunkel's test or tannic acid test: If tannic acid is added to blood it remains cherry-red in CO poisoning, where oxyhemoglobin turns deep brown. Hoppe-Seyler's test is also used to identify CO poisoning. Few drops of blood are added to a solution of 10% sodium hydroxide. Normal blood turns brownish-green, but if CO is present, the color will remain pink. Ref: The Essentials of Forensic Medicine and Toxicology by KS Narayan Reddy, 27th edition, Page 555.", 'role': 'assistant'}]