Main enzyme of transcription-

Options

A. DNA dependent DNA polymerase
B. DNA dependent RNA polymerase
C. RNA dependent RNA polymerase
D. RNA dependent DNA polymerase

Answer

### Step-by-Step Solution:

1. **Understanding Transcription**:
- Transcription is the biological process where RNA is synthesized from a DNA template. This process is crucial for gene expression, as it converts the genetic information stored in DNA into a format that can be used to produce proteins.

2. **Identifying the Main Enzyme**:
- The main enzyme responsible for transcription is crucial to know. This enzyme catalyzes the synthesis of RNA from the DNA template.

3. **Evaluating the Options**:
- **Option A: DNA dependent DNA polymerase**: This enzyme synthesizes DNA from a DNA template, which is not what we need for transcription. Therefore, this option is incorrect.
- **Option B: DNA dependent RNA polymerase**: This enzyme synthesizes RNA from a DNA template, which is exactly what we need for transcription. This option is correct.
- **Option C: RNA dependent RNA polymerase**: This enzyme synthesizes RNA from an RNA template, which is not involved in the transcription process from DNA to RNA. Thus, this option is incorrect.
- **Option D: RNA dependent DNA polymerase**: This enzyme, known as reverse transcriptase, synthesizes DNA from an RNA template. This is not relevant to the transcription process we are discussing. Therefore, this option is also incorrect.

4. **Conclusion**:
- After evaluating all the options, the correct answer to the question "Main enzyme of transcription" is **Option B: DNA dependent RNA polymerase**.