Assertion : Cryolite is used in electrolytic extraction of Al from alumina.
It dissolves alumina.

Options

A. If both assetion and reason are CORRECT, and reason is the CORRECT explanation of the assertion
B. If both assertion and reason are CORRECT, but reason is NOT the CORRECT explanation of the assertion
C. If assertion is CORRECT but reason is INCORRECT
D. If assertion is INCORRECT but reason is CORRECT

Answer

### Step-by-Step Text Solution

1. **Understanding the Assertion**: The assertion states that "Cryolite is used in electrolytic extraction of Al from alumina." This is indeed true. Cryolite (Na3AlF6) is used in the Hall-Héroult process, which is the primary method for extracting aluminum from its ore, bauxite (which is primarily aluminum oxide, Al2O3).

2. **Understanding the Reason**: The reason provided is that "It dissolves alumina." This is also true. Cryolite acts as a solvent for alumina in the molten state, allowing for a more efficient electrolytic extraction process.

3. **Evaluating the Relationship**: Now, we need to evaluate whether the reason correctly explains the assertion. In this case, the reason does explain why cryolite is used in the process: it dissolves alumina, which is essential for the electrolytic extraction to occur effectively.

4. **Conclusion**: Since both the assertion and the reason are correct, and the reason provides a correct explanation for the assertion, we conclude that both statements are true and the reason is a correct explanation of the assertion.

5. **Final Answer**: Therefore, the correct option is that both the assertion and reason are correct, and the reason is a correct explanation of the assertion.