Chronic obstructive pulmonary disease (COPD) comprises chronic bronchitis and emphysema. Which sequence is correct as emphysema develops? 1 Macrophages move into the alveolar air spaces. 2 Tar paralyses cilia. 3 Macrophages secrete elastase. 4 Bacteria build up in the alveoli.
- A2 → 4 → 1 → 3
- B2 → 4 → 3 → 1
- C4 → 1 → 3 → 2
- D4 → 2 → 3 → 1