Ribosomal subunits and rRNA are synthesized in which site of nucleus ?

Options

A. Nucleolous
B. Cytoplasm
C. Nucleoplasm
D. Perinuclear Space

Answer

### Step-by-Step Solution:

1. **Understanding Ribosomal Subunits and rRNA**: Ribosomal subunits are essential components of ribosomes, which are the cellular machinery responsible for protein synthesis. Ribosomal RNA (rRNA) is a key part of these subunits.

2. **Identifying the Sites in the Nucleus**: The question asks where ribosomal subunits and rRNA are synthesized within the nucleus. The options provided are:
- Nucleolus
- Spectroplasm
- Nucleoplasm
- Perinuclear space

3. **Function of the Nucleolus**: The nucleolus is a distinct region within the nucleus that is primarily responsible for the synthesis of rRNA and the assembly of ribosomal subunits. It is where the genes encoding rRNA are transcribed and processed.

4. **Role of Ribosomal Proteins**: Ribosomal proteins, which are synthesized in the cytoplasm, migrate into the nucleus where they combine with rRNA to form the ribosomal subunits in the nucleolus.

5. **Final Answer**: Based on the above information, the correct answer to the question is **Nucleolus**.