Narrowing of the airways occurs in which condition?

Bronchial asthma is characterized by the narrowing of the airways due to inflammation, bronchoconstriction, and increased mucus production. This condition leads to episodes of wheezing, shortness of breath, chest tightness, and coughing, especially during nighttime or early morning. The inflammation of the airways makes them hyperresponsive to various triggers such as allergens, pollution, and exercise, causing them to constrict and effectively narrow the passage through which air can flow.

In contrast, Crohn's disease primarily affects the gastrointestinal tract and does not involve the airways. Alzheimer's disease is a progressive neurological disorder that impacts memory and cognitive function, with no direct correlation to airway function. Pneumonia, while it can cause breathing difficulties due to fluid in the lungs, does not cause the chronic airway narrowing associated with asthma. Thus, bronchial asthma is the correct answer, as it directly involves the anatomical and physiological changes leading to airway constriction.