Which of the following describes emphysema?

Emphysema is a progressive lung disease that primarily involves the destruction of the alveoli, the small air sacs in the lungs where gas exchange occurs. This destruction leads to a significant reduction in the surface area available for oxygen and carbon dioxide exchange, which results in respiratory insufficiency. Patients with emphysema often experience shortness of breath, especially during physical activity, and may struggle to exhale air from their lungs due to the loss of elasticity in lung tissue.

The other options do not accurately describe emphysema. Mild respiratory infections are typically temporary conditions that cause symptoms such as coughing or congestion but do not involve permanent lung damage like emphysema. Heart disease refers to a range of conditions affecting the heart, which are distinct from lung diseases. Lastly, cancer refers to the uncontrolled growth of abnormal cells and encompasses many specific types, none of which are descriptive of emphysema or its effects on lung tissue. Thus, the focus on the destruction of lung tissue in emphysema makes it correctly categorized as a serious condition affecting respiratory function.