Destruction of the wall of the alveoli is:

Correct option is C

Emphysema is a chronic lung condition where alveolar walls are destroyed, reducing gas exchange surface area, often caused by smoking. Explanation of options:
· (a) ✘ Atelectasis is lung collapse, not wall destruction.
· (b) ✘ Asthma is airway inflammation and narrowing, not alveolar damage.
· (c) ✔ Correct; alveolar wall destruction is hallmark of emphysema.
· (d) ✘ Bronchiectasis involves dilation of bronchi, not alveoli.