Number of stomata is 30 and epidermal cells 120 per unit area of a leaf. The stomatal index is

Options

A. 0.05
B. 0.5
C. 0.2
D. 0.02

Answer

To find the stomatal index, we can use the formula:

**Stomatal Index (SI) = (S / (E + S)) × 100**

Where:
- S = Number of stomata
- E = Number of epidermal cells

### Step-by-Step Solution:

1. **Identify the values for S and E:**
- Number of stomata (S) = 30
- Number of epidermal cells (E) = 120

2. **Plug the values into the formula:**
- SI = (30 / (120 + 30)) × 100

3. **Calculate the denominator:**
- E + S = 120 + 30 = 150

4. **Substitute the denominator back into the formula:**
- SI = (30 / 150) × 100

5. **Perform the division:**
- 30 / 150 = 0.2

6. **Multiply by 100 to find the percentage:**
- SI = 0.2 × 100 = 20

7. **Write the final answer:**
- The stomatal index is 20%.

### Conclusion:
- The stomatal index, without the percentage, is 0.2.

### Final Answer:
- The correct option is 0.2 (Option 3).