Assertion : The maxiumum frequency of recombination, that can result from crossing over between linked genes is 50 percent
Reason : Linked genes shown higher frequency of crossing over if distance between them is longer.

Options

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

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the maximum frequency of recombination that can result from crossing over between linked genes is 50%.
- This is true because linked genes are located close to each other on the same chromosome. If they are completely linked, they will not recombine, resulting in a frequency of recombination less than 50%. However, if they are unlinked (or assort independently), the maximum frequency of recombination can reach 50%.

2. **Understanding the Reason**:
- The reason states that linked genes show a higher frequency of crossing over if the distance between them is longer.
- This statement is also true. The further apart two genes are on a chromosome, the more likely it is that a crossover event will occur between them, leading to a higher frequency of recombination. Therefore, the frequency of crossing over is indeed influenced by the distance between linked genes.

3. **Evaluating the Relationship**:
- While both the assertion and reason are true, the reason does not correctly explain the assertion. The assertion is about the maximum frequency of recombination being 50%, while the reason discusses the relationship between the distance of linked genes and the frequency of crossing over.

4. **Conclusion**:
- Since both statements are true but the reason does not provide a correct explanation for the assertion, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
The correct answer is **B**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.