**Core Concept**
Lung compliance refers to the ability of the lungs to expand and fill with air, which is crucial for maintaining adequate gas exchange. It is an essential parameter in pulmonary physiology, influencing total lung capacity (TLC) and overall respiratory function.

**Why the Correct Answer is Right**
Lung compliance is directly related to the elastic properties of the lungs and chest wall. A higher lung compliance allows for greater expansion of the lungs during inspiration, resulting in a larger total lung capacity. This is because compliance determines the ease with which the lungs can be inflated, and a higher compliance means that the lungs can be inflated more easily, thereby increasing TLC. The lungs' ability to expand is also influenced by the presence of surfactant, which reduces surface tension and facilitates easier lung expansion.

**Why Each Wrong Option is Incorrect**
**Option A:** The size of the airway does not directly influence total lung capacity. While the diameter of the airway affects airflow resistance, it does not impact the lungs' ability to expand and fill with air.

**Option B:** Closing tidal volume refers to the volume of air remaining in the lungs at the end of a normal exhalation. While it is an important parameter, it does not directly affect total lung capacity.

**Option D:** Residual volume is the volume of air remaining in the lungs after a maximal exhalation. Although it is an essential component of lung function, it does not determine total lung capacity.

**Clinical Pearl / High-Yield Fact**
Understanding lung compliance is critical in managing patients with respiratory diseases, such as chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis. A decrease in lung compliance can lead to increased work of breathing and reduced lung volumes, making it essential to assess lung function in these patients.

**✓ Correct Answer: C. Lung compliance**