In lung , maximum gaseous exchange is due to
(a) Simple diffusion
(b) Active transport
(c) Passive transport
(d) Facillitated diffusion

Options

A. Simple diffusion
B. Active transport
C. Passive transport
D. Fascillitated diffusion

Answer

To solve the question regarding the maximum gaseous exchange in the lungs, we need to analyze the options provided and understand the physiological processes involved in gas exchange.

### Step-by-Step Solution:

1. **Understanding the Structure of the Lungs**:
- The lungs contain tiny air sacs called alveoli, which are the primary sites for gas exchange.

2. **Identifying the Process of Gas Exchange**:
- Gas exchange in the alveoli occurs between the air in the alveoli and the blood in the capillaries surrounding them.

3. **Analyzing the Options**:
- **(a) Simple diffusion**: This is the process where gases move from an area of higher concentration to an area of lower concentration without the need for energy or a carrier protein.
- **(b) Active transport**: This process requires energy to move substances against their concentration gradient, which is not how gases exchange in the lungs.
- **(c) Passive transport**: This is a broader term that includes simple diffusion, but it does not specifically refer to the mechanism of gas exchange.
- **(d) Facilitated diffusion**: This involves the use of carrier proteins to help move substances across a membrane, which is not the primary method for gas exchange in the lungs.

4. **Conclusion**:
- The maximum gaseous exchange in the lungs occurs primarily through **simple diffusion** due to the concentration gradient of oxygen and carbon dioxide. Therefore, the correct answer is **(a) Simple diffusion**.

### Final Answer:
**(a) Simple diffusion**