**Core Concept**
Obstructive lung disease refers to a group of conditions characterized by airflow limitation due to airway obstruction, leading to decreased lung function and increased symptoms such as wheezing, coughing, and shortness of breath. The primary pathophysiological mechanism involves airway inflammation, hyperresponsiveness, and remodeling, which result in airway narrowing and obstruction.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of obstructive lung disease. In obstructive lung disease, there is an increase in airway resistance due to airway constriction and inflammation. This leads to a decrease in forced expiratory volume (FEV1) and forced vital capacity (FVC) ratio, indicating airway obstruction. The airway obstruction is often due to chronic inflammation and hyperresponsiveness of the airways, leading to symptoms such as wheezing, coughing, and shortness of breath.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a characteristic of obstructive lung disease, not an exception. Airway obstruction is a hallmark of obstructive lung disease.

**Option B:** This option is incorrect because it is a characteristic of obstructive lung disease, not an exception. Hyperresponsiveness of the airways is a key feature of obstructive lung disease.

**Option C:** This option is incorrect because it is a characteristic of obstructive lung disease, not an exception. Airway inflammation is a primary pathophysiological mechanism in obstructive lung disease.

**Clinical Pearl / High-Yield Fact**
A key clinical correlation in obstructive lung disease is the use of spirometry to diagnose and monitor disease progression. Spirometry measures lung function by assessing the volume and flow of air in and out of the lungs, providing valuable information for diagnosing and managing obstructive lung disease.

**Correct Answer: D**