Which of the following describes chronic bronchitis?

Chronic bronchitis is primarily characterized by airflow obstruction, which results from chronic inflammation of the bronchial tubes. This inflammation leads to increased mucus production and narrowing of the airways, making it difficult for air to flow in and out of the lungs effectively. Over time, the persistent cough and sputum production that define chronic bronchitis contribute to this obstruction.

In contrast, decreased lung volumes, while potentially relevant to many respiratory diseases, are not the hallmark of chronic bronchitis; rather, they may better characterize restrictive lung diseases. Reversible symptoms are more indicative of asthma, where airway obstruction can improve with bronchodilators. Normal airway function does not apply to chronic bronchitis, as the condition inherently involves impaired airflow due to the pathological changes in the airways. Therefore, the defining characteristic of airflow obstruction is a fundamental aspect of chronic bronchitis.