## **Core Concept**
Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. It is the sum of the residual volume (RV) and the expiratory reserve volume (ERV). FRC helps in maintaining the airway patency and facilitating gas exchange.

## **Why the Correct Answer is Right**
The typical value for FRC in an average adult male is approximately 2300 mL or 2.3 liters. This value represents the volume of air left in the lungs after a normal, relaxed exhalation. It is crucial for understanding lung volumes and capacities in respiratory physiology.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Values significantly lower than 2.3 liters would not accurately represent FRC for an average male, as it would be too low for a typical adult.
- **Option B:** Similarly, values much higher or lower than 2.3 liters would not be correct for FRC in a male.
- **Option D:** This option suggests a value that might be more characteristic of other lung volumes or capacities, not FRC.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that FRC is decreased in conditions like restrictive lung diseases (e.g., pulmonary fibrosis) and increased in obstructive lung diseases (e.g., COPD). Understanding FRC and other lung volumes is critical for diagnosing and managing respiratory diseases.

## **Correct Answer:** C. 2300 mL.