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
Inability to perform physical activity without discomfo falls under 
Select and explain. 
A. NYHA class 1, B. NYHA class 2, C. NYHA class 3, D. NYHA class 4
D: NYHA class 4
Answer: D: NYHA class 4 
Explanation: Ans. d. NYHA class 4