Assertion: WBCs accumulate at site of wounds by diapedesis.
Reason: It is squeezing of leucocytes from endotheium.

Options

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

Explanation

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

### Step 1: Understand the Assertion
The assertion states: "WBCs accumulate at the site of wounds by diapedesis."
- Diapedesis is the process through which white blood cells (WBCs) move out of the bloodstream and into the tissues, particularly at sites of injury or infection. This process is crucial for the immune response.

### Step 2: Understand the Reason
The reason states: "It is squeezing of leucocytes from endothelium."
- The reason describes the mechanism of diapedesis, where leukocytes (another term for WBCs) squeeze through the endothelial cells lining the blood vessels to reach the site of injury.

### Step 3: Evaluate the Truth of Assertion and Reason
- Both the assertion and the reason are true statements. WBCs do accumulate at the site of wounds through diapedesis, and this involves the squeezing of leukocytes from the endothelium.

### Step 4: Determine the Relationship Between Assertion and Reason
- While both statements are true, the reason does not correctly explain the assertion. Diapedesis is a response to the presence of foreign agents or signals from the site of injury, not merely a mechanical squeezing of leukocytes by the endothelium.

### Conclusion
- The assertion is true, and the reason is true, but the reason is not the correct explanation for the assertion. Therefore, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion.

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

---