Assertion : If a piece of DNA to be propagated during recombinant DNA procedures requires a vector.
Reason : Vector provides ori.

Options

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

Explanation

To address the assertion and reason provided in the question, we need to analyze both statements carefully.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that a piece of DNA requires a vector to be propagated during recombinant DNA procedures.
- In molecular biology, a vector is a DNA molecule used to deliver genetic material into a cell. Vectors are essential for cloning, as they allow for the replication of the DNA fragment of interest.

2. **Understanding the Reason**:
- The reason given is that a vector provides an origin of replication (ori).
- The origin of replication is a specific sequence in a genome at which replication is initiated. Vectors typically contain an ori to ensure that they can replicate independently within a host cell.

3. **Connecting the Assertion and Reason**:
- The assertion is true because vectors are indeed necessary for the propagation of DNA in recombinant DNA technology.
- The reason is also true because vectors do provide an ori, which is crucial for the replication of the inserted DNA.

4. **Conclusion**:
- Since both the assertion and the reason are true, and the reason correctly explains why the assertion is true, we can conclude that the statement is valid.

### Final Answer:
Both the assertion and the reason are true, and the reason correctly explains the assertion.

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