Which of the following are characteristics of asthma?

Asthma is characterized by increased sensitivity of the lower airways to various irritants, which leads to bronchospasm and airway edema. In an individual with asthma, exposure to allergens, irritants, or respiratory infections can trigger an exaggerated inflammatory response. This results in the constriction of airway muscles (bronchospasm) and swelling of the airway walls (edema), which impedes airflow and causes symptoms such as wheezing, shortness of breath, and chest tightness.

The other choices describe conditions that do not align with asthma. For example, an acute infectious disease that involves lung inflammation and pus-filled alveoli points towards pneumonia. A persistent productive cough, thickening of bronchial walls, and excessive mucus can be associated with chronic obstructive pulmonary disease (COPD) rather than asthma. Finally, the destruction of alveolar walls and distention of alveolar sacs, leading to reduced gas exchange area, is characteristic of emphysema, another form of COPD. These conditions are distinct and exhibit different pathophysiological mechanisms compared to asthma.