This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: COPD and Asthma, Subject name: Medicine
[{'content': 'All are seen in chronic bronchitis except: \nSelect and explain. \nA. Cough > 3 months, B. Bronchorrhea, C. Hoover sign, D. Clubbing', 'role': 'user'}, {'content': "Answer: D \nExplanation: The most common symptoms of COPD- cough, sputum production, and exeional dyspnea. Some patients with advanced disease have paradoxical inward movement of the rib cage with inspiration (Hoover's sign), the result of alteration of the vector of diaphragmatic contraction on the rib cage as a result of chronic hyperinflation. Clubbing is not seen in Chronic bronchitis", 'role': 'assistant'}]