Assertion (A) : Ti plasmid (tumour-inducing plasmid) of Agrobacterium tumefaciens is used as a cloning vector.
Reason (R): Ti plasmid integrates a segment of its DNA, termed T-DNA into the chromosomal DNA of its host plant cells.

Options

A. Both assertion (A) and reason (R ) are true and reason (R ) is the correct explanation of assertion (A ) .
B. Both assertion (A) and reason ( R) are true but reason (R ) is not the correct explaination of assertion (A ) .
C. Assertion (A) is true but reason (R ) is false .
D. Assertion (A ) is false but reason (R ) is true.

Explanation

To analyze the assertion and reason provided, we can follow these steps:

### Step 1: Understand the Assertion
The assertion states that the Ti plasmid (tumour-inducing plasmid) of Agrobacterium tumefaciens is used as a cloning vector.

- **Explanation**: Ti plasmids are indeed utilized in genetic engineering as vectors to introduce foreign DNA into plant cells. They are particularly effective because they can naturally transfer DNA into the plant genome.

### Step 2: Understand the Reason
The reason given is that the Ti plasmid integrates a segment of its DNA, termed T-DNA, into the chromosomal DNA of its host plant cells.

- **Explanation**: This statement is also true. The T-DNA region of the Ti plasmid is transferred and integrated into the plant cell's chromosomal DNA, which is a crucial step in the process of genetic modification in plants.

### Step 3: Determine the Relationship between Assertion and Reason
Now we need to evaluate whether the reason provided is a correct explanation for the assertion.

- **Analysis**: While both the assertion and reason are true, the reason does not directly explain why the Ti plasmid is used as a cloning vector. The use of Ti plasmid as a cloning vector is based on its ability to transfer genes into plants, but the reason focuses on the integration of T-DNA into the plant genome.

### Conclusion
Based on the analysis:
- Both the assertion (A) and the reason (R) are true.
- However, the reason (R) is not the correct explanation for the assertion (A).

Thus, the correct answer is that both assertion A and reason R are true, but reason R is not the correct explanation of assertion A.

### Final Answer
Both assertion A and reason R are true, but reason R is not the correct explanation of assertion A.

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