Assertion : Plasmids are double-stranded extra chromosomal DNA.
Reason : Plasmids are possessed by eukaryotic cells.

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the given question, we need to analyze the assertion and the reason provided:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Plasmids are double-stranded extra chromosomal DNA."
- This statement is true. Plasmids are indeed double-stranded and exist outside the chromosomal DNA in cells. They are typically circular in shape and are found in many bacteria.

2. **Understanding the Reason**:
- The reason states that "Plasmids are possessed by eukaryotic cells."
- This statement is false. While plasmids are primarily associated with prokaryotic cells (like bacteria), they can also be found in some eukaryotic organisms, particularly in certain fungi and plants. However, the assertion is more commonly associated with prokaryotes.

3. **Conclusion**:
- Since the assertion is true and the reason is false, we conclude that the correct answer is that the assertion is true, but the reason is false.

### Final Answer:
- Assertion (A) is true.
- Reason (R) is false.
- Therefore, the answer is: A is true, R is false.

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