The enzyme released by restriction protection system in bacterial cells that ensures safety of self DNA is :

Options

A. DNA polymerase
B. ligase
C. methylase
D. restriction endonuclease

Answer

To solve the question regarding the enzyme released by the restriction protection system in bacterial cells that ensures the safety of self DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the specific enzyme involved in the restriction protection system in bacteria that protects their own DNA from being degraded.

2. **Analyze the Options**: The options given are:
- DNA polymerase
- Ligase
- Methylase
- Restriction endonuclease

3. **Evaluate Each Option**:
- **DNA Polymerase**: This enzyme is primarily involved in DNA replication and repair. It does not play a role in protecting bacterial DNA from restriction enzymes. Thus, it is not the correct answer.
- **Ligase**: This enzyme is responsible for joining two large molecules by forming new chemical bonds. It does not have a role in the restriction protection system. Therefore, this option is also incorrect.
- **Restriction Endonuclease**: This enzyme is produced by bacteria to cleave DNA at specific sites. While it is involved in the restriction system, it does not protect the bacterial DNA; instead, it acts against foreign DNA. Hence, this is not the correct answer.
- **Methylase**: This enzyme adds methyl groups to specific sites on the bacterial DNA. By doing so, it protects the bacterial DNA from being cleaved by restriction endonucleases, which would otherwise target unmethylated DNA. This is the correct answer.

4. **Conclusion**: The enzyme that ensures the safety of self DNA in bacterial cells by the restriction protection system is **Methylase**.

### Final Answer:
The enzyme released by the restriction protection system in bacterial cells that ensures safety of self DNA is **Methylase**.