Bronchiolitis primarily involves which part of the airway?

• A. Small bronchi
• B. Large airways
• C. Alveolar sacs
• D. Pleura

Answer: (A)

Bronchiolitis inflames the small airways, the bronchioles, causing swelling and mucus buildup that narrow these tiny passages. This makes the bronchioles the primary site of involvement, which is why the best choice is the small airways. Inflammation of large airways would point to conditions like croup or tracheitis, involvement of the alveolar sacs would relate to pneumonia or alveolar processes, and the pleura is the lung lining, not the site of bronchiolar inflammation.