This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Physiology
[{'content': 'Cyanosis is not seen in \nSelect and explain. \nA. CHF, B. COPD, C. CO poisoning, D. High altitude', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cyanosis is a bluish discoloration of the skin and mucous membranes resulting from inadequate oxygenation of the blood and not seen in CO poisoningRef: Hutchison&;s Clinical Methods, 23ed edition, page no: 21', 'role': 'assistant'}]