Site for active ribosomal RNA synthesis in nucleus is

Options

A. Nucleoplasm
B. Chromatin
C. Nucleolus
D. Nuclear envelope

Answer

To answer the question regarding the site for active ribosomal RNA synthesis in the nucleus, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components of the Nucleus**: The nucleus contains several components, including nucleoplasm, chromatin, nucleolus, and nuclear envelope. Each of these has distinct functions.

2. **Identify the Function of Each Component**:
- **Nucleoplasm**: This is the protoplasm within the nucleus, where various nuclear components are suspended.
- **Chromatin**: This is the material that makes up chromosomes, consisting of DNA and proteins. It is involved in packaging DNA and regulating gene expression.
- **Nucleolus**: This is a dense, round structure within the nucleus that is primarily responsible for the synthesis of ribosomal RNA (rRNA).
- **Nuclear Envelope**: This is the double membrane that surrounds the nucleus, providing a barrier between the nucleus and the cytoplasm.

3. **Focus on Ribosomal RNA Synthesis**: Ribosomal RNA (rRNA) is a crucial component of ribosomes, which are essential for protein synthesis. The synthesis of rRNA occurs in a specific region of the nucleus.

4. **Identify the Correct Structure**: Among the components listed, the nucleolus is specifically known for its role in synthesizing rRNA. It contains the necessary genes that encode for rRNA, making it the site of active ribosomal RNA synthesis.

5. **Conclude with the Correct Answer**: Based on the functions and characteristics of the components of the nucleus, the correct answer to the question is the **nucleolus**.

### Final Answer:
The site for active ribosomal RNA synthesis in the nucleus is the **nucleolus**.

---