Which condition is NOT classified as an obstructive lung disease?

Sarcoidosis is a condition that is characterized by the growth of small clusters of inflammatory cells in various organs, most commonly the lungs. It typically presents with restrictive lung function changes rather than obstructive changes. In restrictive lung disease, the lung tissue may be stiff or swollen, restricting lung expansion and making it difficult for the lungs to hold air, which contrasts with obstructive lung diseases where the airflow is blocked during exhalation due to conditions that affect the bronchial tubes.

On the other hand, conditions like asthma, chronic bronchitis, and emphysema are classic examples of obstructive lung disease. Asthma involves reversible airway obstruction due to inflammation and bronchoconstriction; chronic bronchitis leads to insufficient airflow due to mucus production and airway inflammation; and emphysema results from the destruction of alveoli and loss of elastic recoil, severely limiting airflow during exhalation. Thus, while conditions A, B, and D are all classified as obstructive lung diseases, sarcoidosis does not fall into this category, making it the correct choice in this question.