Plasmid contains

Options

A. ds circular DNA
B. ss circular DNA
C. ds linear DNA
D. ss linear DNA

Answer

### Step-by-Step Solution:

1. **Understanding Plasmids**: Plasmids are small, circular pieces of DNA that are found in bacteria and some other organisms. They are distinct from the chromosomal DNA that makes up the main genetic material of the organism.

2. **Characteristics of Plasmids**:
- **Extra Chromosomal DNA**: Plasmids exist outside of the chromosomal DNA, which means they are not part of the main genome.
- **Independent Replication**: Plasmids can replicate independently of the chromosomal DNA, allowing them to be passed on during cell division.

3. **Structure of Plasmids**:
- **Circular DNA**: The DNA in plasmids is circular in shape, which is a common characteristic of DNA found in prokaryotes (like bacteria).
- **Double-Stranded**: Plasmid DNA is composed of two strands, making it double-stranded, similar to the chromosomal DNA.

4. **Function of Plasmids**:
- Plasmids often carry genes that provide beneficial traits to the bacteria, such as antibiotic resistance or the ability to metabolize certain substances.

5. **Conclusion**: Based on the characteristics and structure of plasmids, we can conclude that plasmids contain double-stranded circular DNA.

### Final Answer:
Plasmids contain **double-stranded circular DNA**.

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