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': 'Inability to perform physical activity without discomfo falls under \nSelect and explain. \nA. NYHA class 1, B. NYHA class 2, C. NYHA class 3, D. NYHA class 4', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. d. NYHA class 4', 'role': 'assistant'}]