About 1200 mL of air is always known to remain inside the human lungs it is described as

Options

A. functional residual capactiy
B. residual volume
C. expiratory reserve volume
D. inspiratory reserve volume

Answer

To solve the question about the 1200 mL of air that remains inside the human lungs, we will analyze the options provided and understand the definitions of each term related to lung volumes.

### Step-by-Step Solution:

1. **Understanding the Question**: The question states that about 1200 mL of air remains in the human lungs. We need to identify the term that describes this volume.

2. **Reviewing the Options**:
- **Functional Residual Capacity (FRC)**: This is the volume of air remaining in the lungs after a normal expiration. It includes both the residual volume and the expiratory reserve volume. The range for FRC is typically between 1.7 to 3.5 liters.
- **Residual Volume (RV)**: This is the volume of air that remains in the lungs after a forceful expiration. The typical value for residual volume is about 1200 mL.
- **Expiratory Reserve Volume (ERV)**: This is the volume of air that can be forcibly exhaled after the end of a normal expiration. This volume is also around 1200 mL but is not the volume that remains in the lungs.
- **Inspiratory Reserve Volume (IRV)**: This is the volume of air that can be forcibly inhaled after a normal inhalation. The typical value for inspiratory reserve volume is around 3000 mL.

3. **Identifying the Correct Answer**:
- Since the question specifically mentions that 1200 mL of air remains in the lungs, we look at the definitions. The residual volume (RV) is the air that remains after a forceful expiration and is specifically noted to be around 1200 mL.
- Functional residual capacity includes residual volume but is not limited to it. Expiratory reserve volume is the amount of air that can be exhaled but does not represent what remains in the lungs after expiration.

4. **Conclusion**: Based on the definitions and the specific volume mentioned in the question, the correct answer is **Residual Volume (RV)**.

### Final Answer:
**Residual Volume (RV)**

---