Guard cells :
a. Enclose stomatal pore
b. Are dumb - bell shaped in dicots
c. Outer wall thick and inner wall thin
d. Regulates opening and closing of stomata
1 a & b are correct
2 a & d are incorrect
3 b & c are incorrect
4 c & d are correct

Options

A. a & b are correct
B. a & d are incorrect
C. b & c are incorrect
D. c & d are correct

Answer

To solve the question regarding guard cells, we need to evaluate each statement provided:

1. **Statement A**: "Enclose stomatal pore."
- **Analysis**: Guard cells are specialized cells that surround the stomatal pore and regulate its opening and closing. Therefore, this statement is **correct**.

2. **Statement B**: "Are dumb-bell shaped in dicots."
- **Analysis**: In dicots, guard cells are typically bean-shaped, not dumb-bell shaped. The dumb-bell shape is characteristic of monocots. Therefore, this statement is **incorrect**.

3. **Statement C**: "Outer wall thick and inner wall thin."
- **Analysis**: The guard cells have a thick inner wall and a thin outer wall. Thus, this statement is also **incorrect**.

4. **Statement D**: "Regulates opening and closing of stomata."
- **Analysis**: The primary function of guard cells is to regulate the opening and closing of the stomatal pore, which is essential for gas exchange. Therefore, this statement is **correct**.

Now, let's summarize the correctness of each statement:
- **A**: Correct
- **B**: Incorrect
- **C**: Incorrect
- **D**: Correct

Based on the evaluations:
- Statements B and C are incorrect.

Thus, the correct answer to the question is **Option 3: b & c are incorrect**.