**Core Concept**
Surfactant is a complex mixture of lipids and proteins that lines the alveoli of the lungs, playing a crucial role in reducing surface tension and facilitating gas exchange. The main functions of surfactant include reducing alveolar collapse, improving lung compliance, and preventing alveolar edema.

**Why the Correct Answer is Right**
Surfactant functions include reducing surface tension, preventing alveolar collapse, improving lung compliance, and facilitating gas exchange. It also helps to prevent alveolar edema and promotes the clearance of debris and pathogens from the alveoli.

**Why Each Wrong Option is Incorrect**
* **Option A:** (This option is not provided, so we'll skip it)
* **Option B:** (This option is not provided, so we'll skip it)
* **Option C:** (This option is not provided, so we'll skip it)
* **Option D:** (This option is not provided, so we'll skip it)

Since no incorrect options were provided, we cannot explain why each is wrong.

**Clinical Pearl / High-Yield Fact**
Surfactant deficiency or dysfunction can lead to respiratory distress syndrome (RDS) in premature infants, characterized by alveolar collapse, hypoxemia, and respiratory failure.

**Correct Answer:** D.