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': 'Physiological response to smoking, are all, except \nSelect and explain. \nA. Decreased HDL, B. Increased hematocrit, C. Increased hea rate and increased catecholamine release, D. Decreased carboxyhemoglobin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Carboxyhemoglobin increases in smokers Ref: guyton and hall textbook of medical physiology 12 edition page number:353,354,355', 'role': 'assistant'}]