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: Medicine
[{'content': 'Respiratory acidosis is characterized by - \nSelect and explain. \nA. Raised PCO2 and elevated pH, B. Decreased plasma HCO3 and decreased PCO2, C. Increased PCO2 and decreased pH, D. Decreased pH and decreased PCO2', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]