Nucleolus is :

Options

A. Rounded structure found in cytoplasm near nucleus
B. Rounded structure inside nucleus and having rRNA
C. Rod - shaped structure in cytoplasm near the nucleus
D. None of the above

Answer

To solve the question "Nucleolus is:", we will analyze the provided options and identify the correct description of the nucleolus.

### Step-by-Step Solution:

1. **Understanding the Nucleolus**:
- The nucleolus is a prominent sub-structure within the nucleus of eukaryotic cells. It is not found in the cytoplasm but is located inside the nucleus.

2. **Identifying the Structure**:
- The nucleolus is characterized as a rounded structure. It is not rod-shaped or any other shape.

3. **Function of the Nucleolus**:
- The nucleolus is primarily involved in the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomes, which are essential for protein synthesis in the cell.

4. **Evaluating the Options**:
- **Option A**: "Rounded structure found in cytoplasm near nucleus" - Incorrect, as it is located inside the nucleus, not in the cytoplasm.
- **Option B**: "Rounded structure inside nucleus and having ribosomal RNA" - Correct, as it accurately describes the nucleolus.
- **Option C**: "Rod-shaped structure in cytoplasm near the nucleus" - Incorrect, as the nucleolus is not rod-shaped and is not found in the cytoplasm.
- **Option D**: "None of the above" - Incorrect, since option B is correct.

5. **Conclusion**:
- The correct answer is **Option B**: "Rounded structure inside nucleus and having ribosomal RNA".