The process of formation of secondary meristem from primary permanent tissue is called:-

Options

A. Differentation
B. Dedifferentation
C. Redifferentation
D. Secretion

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the process through which secondary meristem is formed from primary permanent tissue.

2. **Defining Key Terms**:
- **Meristem**: These are regions of plant tissue that are capable of continuous growth and can divide to form new cells.
- **Permanent Tissue**: This is tissue that has lost the ability to divide and has differentiated into specific functions.

3. **Differentiation**: This is the process where meristematic tissue converts into permanent tissue. Once cells differentiate, they lose their ability to divide.

4. **De-differentiation**: This is the process where differentiated cells (permanent tissue) regain the ability to divide and revert back to a meristematic state. This is crucial for the formation of secondary meristems.

5. **Re-differentiation**: This occurs when de-differentiated meristematic cells again differentiate into permanent tissue. This process is a repetition of differentiation.

6. **Secretion**: This term refers to the process of releasing substances such as sap or nutrients, which is not relevant to the formation of meristem.

7. **Conclusion**: Since the question specifically asks about the formation of secondary meristem from primary permanent tissue, the correct answer is **de-differentiation**. This process allows the permanent tissue to regain its ability to divide and form new meristematic tissue.

### Final Answer:
The process of formation of secondary meristem from primary permanent tissue is called **de-differentiation**.