I. Transpiration and gaseous exchange occur through stomata
II. Cell wall of guard cells are homogenous in nature
III. Guard cells are regular in shape
IV. Cellulosic microfibrils are longitudinally oriented in guard cells
The correct statements are -

Options

A. All
B. Only IV
C. Only I and III
D. I, II and IV

Answer

To determine which statements about stomata and guard cells are correct, we will evaluate each statement one by one.

### Step-by-Step Solution:

1. **Evaluate Statement I: "Transpiration and gaseous exchange occur through stomata."**
- This statement is correct. Stomata are small openings on the surface of leaves that allow for the exchange of gases (such as oxygen and carbon dioxide) and the process of transpiration, where water vapor is lost from the plant.

2. **Evaluate Statement II: "Cell wall of guard cells are homogeneous in nature."**
- This statement is incorrect. The cell walls of guard cells are not homogeneous. The inner wall of guard cells is thicker than the outer wall, which means they do not have the same structure throughout.

3. **Evaluate Statement III: "Guard cells are regular in shape."**
- This statement is correct. Guard cells have a regular shape. In monocots, they are typically dumbbell-shaped, and in dicots, they also maintain a regular shape, which is essential for their function in regulating stomatal opening and closing.

4. **Evaluate Statement IV: "Cellulosic microfibrils are longitudinally oriented in guard cells."**
- This statement is incorrect. The cellulosic microfibrils in guard cells are arranged radially, not longitudinally. This radial arrangement allows for the flexibility needed for the guard cells to open and close the stomata effectively.

### Conclusion:
- The correct statements are:
- Statement I: Correct
- Statement II: Incorrect
- Statement III: Correct
- Statement IV: Incorrect

Thus, the correct statements are **I and III**.