A: certain proteins of pollen grain identifies the compatible stigma
r: Compatibility protiens are found located in exine

Options

A. if both assetion A reason are true and the reason is the correct explanation of the assertion then mark
B. if both assertion & reason are true and the reason is not the correct explanation of the assertin then mark
C. if assertion is true statement but reason is false then mark
D. if both assertion and reason are false statements then mark

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that certain proteins in the pollen grain identify the compatible stigma. This means that pollen grains have specific proteins that allow them to recognize whether a stigma is suitable for fertilization.

2. **Understanding the Reason**: The reason given is that compatibility proteins are located in the exine of the pollen grain. The exine is the outer layer of the pollen grain, and it plays a crucial role in the recognition process during fertilization.

3. **Analyzing the Interaction**: In flowering plants, the interaction between pollen grains and stigmas is known as pollen-pistil interaction. This interaction involves chemical communication, where the proteins on the pollen grain interact with the stigma to determine compatibility.

4. **Verifying the Assertion**: Since the assertion claims that pollen grains have proteins that help in identifying compatible stigmas, and this is supported by the fact that such recognition is essential for successful fertilization, we can conclude that the assertion is correct.

5. **Verifying the Reason**: The reason states that compatibility proteins are found in the exine. Given that the exine is the outer layer of the pollen grain and is responsible for the interaction with the stigma, this statement is also correct. The presence of these proteins in the exine is necessary for the stigma to recognize the pollen grain.

6. **Conclusion**: Both the assertion and the reason are true. Furthermore, the reason provides a correct explanation for the assertion, as the proteins located in the exine are indeed responsible for the recognition process.

7. **Final Answer**: Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.