[A]: The preparation of recombinant DNA re- quires restriction enzymes.
[R]: Because these are not used to cleave plasmid DNA

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 question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "The preparation of recombinant DNA requires restriction enzymes."
- **Explanation**: Recombinant DNA is formed by combining DNA from two different sources. To create recombinant DNA, we need to cut the DNA at specific locations, which is where restriction enzymes come into play. These enzymes are essential for cutting the DNA to allow for the insertion of foreign DNA.

2. **Understanding the Reason (R)**:
- The reason states, "Because these are not used to cleave plasmid DNA."
- **Explanation**: This statement is incorrect. Restriction enzymes are indeed used to cleave plasmid DNA. Plasmids are circular DNA molecules that can be cut by restriction enzymes to create openings for inserting foreign DNA, which is a crucial step in the preparation of recombinant DNA.

3. **Evaluating the Truth of A and R**:
- From the analysis:
- Assertion (A) is **true** because restriction enzymes are necessary for the preparation of recombinant DNA.
- Reason (R) is **false** because restriction enzymes are used to cleave plasmid DNA.

4. **Conclusion**:
- The correct evaluation of the statements leads us to conclude that:
- A is true.
- R is false.
- Therefore, the answer is that A is true, and R is false.

### Final Answer:
- The assertion (A) is true, and the reason (R) is false.

---