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: Unknown
[{'content': 'Soot in the trachea is a sign of - \nSelect and explain. \nA. Antemortem burn, B. Postmortem burn, C. Asphyxia, D. Carbon mono oxide poisoning', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. Antemortem burn o One of the most important characteristics of antemortem bums is the finding of Soot and carbon particles' in larynx, trachea and may be in lungs. o There is increased carboxy-hemoglobin (> 5%) which gives cherry red color to post-mortem lividity. Presence of carbon particles (soot) in respiratory passages and elevated level of carboxy-hemoglobin confirms that victim was alive when the burn occurred, i.e. ant-mortem burn. o Various levels of cyanide are found in blood, depending upon the materials burning in fire. But the levels are less than 0.3% mg (normal is zero).", 'role': 'assistant'}]