What is emphysema primarily characterized by?

Emphysema is primarily characterized by the destruction of lung tissue, which specifically affects the alveoli, the small air sacs in the lungs responsible for gas exchange. This damage leads to reduced elasticity in the lungs, making it difficult for a person to exhale air fully. As a result, air becomes trapped in the lungs, causing breathing difficulties and reduced oxygen supply to the body.

The other choices refer to symptoms or features that are either not specific to emphysema or describe other respiratory conditions. For example, while recurrent coughing can occur in several lung diseases, it is not a defining characteristic of emphysema itself. Swelling of lung tissue is more associated with conditions like pulmonary edema rather than emphysema. Lastly, increased lung capacity over time does not occur in emphysema; rather, lung capacity tends to decrease due to the destruction of lung tissue. Thus, the primary hallmark of emphysema is indeed the serious destructive process affecting lung tissue.