Bacterial plasmids contain only DNA which is

Options

A. circular, ds
B. cricular, ss
C. linear, ds
D. linear, ss

Answer

To solve the question regarding the nature of bacterial plasmids, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Bacterial Plasmids**:
- Bacterial plasmids are small, extra-chromosomal DNA molecules found in bacteria. They are distinct from the chromosomal DNA that makes up the main genetic material of the bacterium.

2. **Characteristics of Plasmids**:
- Plasmids are known for their ability to replicate independently of the bacterial chromosomal DNA. This means they can reproduce on their own within the bacterial cell.

3. **Structure of Plasmids**:
- The structure of plasmids is crucial. They are typically described as being circular in shape. This circular structure is a key feature that differentiates them from linear DNA.

4. **Strandedness of DNA**:
- Plasmids are double-stranded, meaning they consist of two strands of DNA that wind around each other. This is a common characteristic of most DNA molecules, including those found in bacteria.

5. **Evaluating the Options**:
- Now, let's evaluate the options given in the question:
- **Circular double-stranded**: This matches the characteristics of plasmids.
- **Circular single-stranded**: This is incorrect as plasmids are double-stranded.
- **Linear double-stranded**: This is also incorrect because plasmids are not linear.
- **Linear single-stranded**: This is incorrect for the same reason.

6. **Conclusion**:
- Based on the characteristics of bacterial plasmids, the correct answer is **circular double-stranded DNA**.

### Final Answer:
**The correct answer is: Circular double-stranded DNA.**