Assertion :- Euchromatin is said to be transcriptionally acitve chromatin.
Reason : Due to loose coilling of enchromatin RNA polymerase can easily move up on it.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are trur but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is Flase.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Euchromatin is said to be transcriptionally active chromatin."
- **Explanation**: Euchromatin is a form of chromatin that is less densely packed than heterochromatin. It is associated with active gene transcription because the DNA in euchromatin is accessible to the transcription machinery.

2. **Understanding the Reason**:
- The reason provided is "Due to loose coiling of euchromatin, RNA polymerase can easily move up on it."
- **Explanation**: The loose coiling of euchromatin allows RNA polymerase, the enzyme responsible for synthesizing RNA from a DNA template, to access the DNA strands more easily. This accessibility facilitates the transcription process.

3. **Evaluating the Truth of the Assertion and Reason**:
- Both the assertion and the reason are true statements.
- The assertion is accurate because euchromatin is indeed transcriptionally active.
- The reason is also true because the loose coiling of euchromatin does allow RNA polymerase to move freely, enabling transcription.

4. **Determining the Relationship Between Assertion and Reason**:
- The reason provided explains why the assertion is true. The loose coiling of euchromatin is the mechanism that allows for its transcriptional activity.

5. **Conclusion**:
- Since both the assertion and the reason are true, and the reason correctly explains the assertion, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer:
- Both assertion and reason are true, and the reason is the correct explanation of the assertion.