**Core Concept**
Surfactant is a crucial substance in the lungs that reduces surface tension in the alveoli, thereby facilitating easier expansion during inhalation and preventing alveolar collapse during exhalation. This is essential for maintaining normal respiratory function and preventing conditions such as respiratory distress syndrome (RDS).

**Why the Correct Answer is Right**
Surfactant works by reducing the surface tension of the alveolar fluid, which is primarily composed of phospholipids and proteins. The primary mechanism of action involves the formation of a phospholipid monolayer at the air-liquid interface in the alveoli. This monolayer reduces the surface tension, allowing for easier lung expansion and gas exchange. The surfactant also contains surfactant protein B (SP-B) and surfactant protein C (SP-C), which play a crucial role in the regulation of surfactant function.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the mechanism of action of surfactant. While surfactant does contain phospholipids, its primary mechanism of action is not simply the presence of these molecules.
**Option B:** This option is also incorrect as it does not accurately describe the role of surfactant in reducing surface tension. While surfactant does contain proteins, its primary mechanism of action is not simply the presence of these molecules.
**Option C:** This option is incorrect as it does not accurately describe the role of surfactant in lung function. While surfactant is essential for normal respiratory function, its primary mechanism of action is not simply the prevention of alveolar collapse.

**Clinical Pearl / High-Yield Fact**
Surfactant therapy is a life-saving treatment for premature infants with respiratory distress syndrome (RDS), and it can significantly improve lung function and outcomes.

**Correct Answer:** C.