DNA does not occur in

Options

A. Nucleus
B. Ribosomes
C. Mitochondria
D. Plastids.

Answer

### Step-by-Step Solution:

1. **Identify the Locations of DNA in Cells:**
- DNA is primarily found in three main organelles: the nucleus, mitochondria, and chloroplasts.
- The nucleus contains double-stranded DNA, which is linear in structure.
- Mitochondria and chloroplasts contain circular double-stranded DNA.

2. **Understand the Role of Each Organelle:**
- The **nucleus** is the control center of the cell and houses the genetic material (DNA).
- **Mitochondria** are known as the powerhouses of the cell and also contain their own DNA, which is involved in energy production.
- **Chloroplasts** are found in plant cells and are responsible for photosynthesis; they too have their own DNA.

3. **Identify Organelles Without DNA:**
- Other cellular structures, such as **ribosomes**, do not contain DNA. Ribosomes are responsible for protein synthesis but do not have any genetic material.

4. **Conclusion:**
- Therefore, the answer to the question "DNA does not occur in" is **ribosomes**.