[A]: DNA code is copied in the synthesis of m-RNA.
[R]: tRNA moves out of the nucleus and after attaching on ribosomes form the template

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 regarding the assertion and reason statements about DNA and mRNA synthesis, we will break down the information step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states: "DNA code is copied in the synthesis of m-RNA."
- This statement is true. During the process of transcription, the DNA sequence is used as a template to synthesize messenger RNA (mRNA). The enzyme RNA polymerase reads the DNA strand and synthesizes the mRNA strand complementary to the DNA template.

2. **Understanding the Reason (R)**:
- The reason states: "tRNA moves out of the nucleus and after attaching on ribosomes form the template."
- This statement is false. Transfer RNA (tRNA) does not move out of the nucleus to form a template. Instead, tRNA is involved in translation, where it brings amino acids to the ribosome during protein synthesis. The template for protein synthesis is actually the mRNA, not tRNA.

3. **Evaluating the Relationship**:
- Since the assertion (A) is true and the reason (R) is false, we conclude that the relationship between the two statements does not hold. The reason provided does not correctly explain the assertion.

4. **Final Conclusion**:
- The correct answer to the question is that assertion (A) is true, and reason (R) is false.

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