What is the main type of chronic obstructive pulmonary disease (COPD)?

• A. Emphysema
• B. Bronchiectasis
• C. Asthma
• D. Bronchiolitis obliterans

Answer: (A)

Chronic obstructive pulmonary disease is defined by persistent, not fully reversible airflow limitation caused by long-term exposure to irritants, most commonly cigarette smoke. Emphysema is the lung tissue change that best defines COPD, involving destruction of alveolar walls and loss of elastic recoil. This leads to enlarged airspaces, reduced surface area for gas exchange, and air trapping with hyperinflation—hallmarks of the COPD pattern. While chronic bronchitis is another COPD-associated pattern, emphysema is the standout type because it reflects the parenchymal destruction driving the airflow limitation. The other conditions listed are distinct diseases: bronchiectasis is dilatation of bronchi due to infection/inflammation, asthma is reversible airway hyperresponsiveness, and bronchiolitis obliterans is a small-airways disease not fitting the classic COPD pattern.