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': 'Following are the features of COPD,except: \nSelect and explain. \nA. Residual volume decreases, B. Irreversible airflow limitation, C. Ineffective repair of elastin, D. Includes small airway disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: -Residual volume increases in COPD Chronic obstructive pulmonary disease (COPD) It is a disease characterised by persistent airflow limitation that is usually progressive, and associated with an enhanced inflammatory response. Airflow limitation is almost irreversible Pathogenesis Cigarette smoking is the main trigger It causes recruitment of many inflammatory and immune cells in the lungs Proteases secreted from these cells will breakdown the extracellular matrix Oxidant causes fuher chronic inflammation and damage to the structure of cell Pulmonary emphysema occurs because of the ineffective repair of matrix and elastin.', 'role': 'assistant'}]