Assertion : Zone refining method is very useful for producing semiconductors.
Reason : Semiconductors are of high purity.

Options

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

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Zone refining method is very useful for producing semiconductors." Zone refining is a technique used to purify materials, particularly useful for semiconductors, which require high purity for optimal performance.

2. **Understanding the Reason**: The reason provided is "Semiconductors are of high purity." This statement is true as semiconductors must be of high purity to function effectively in electronic devices.

3. **Analyzing the Relationship**: We need to determine if the reason provided explains the assertion. While both statements are true, the reason does not directly explain why zone refining is useful for semiconductors. Instead, it states a characteristic of semiconductors.

4. **Conclusion**: Since both the assertion and the reason are true, but the reason does not serve as the correct explanation for the assertion, we can conclude that the correct option is that both assertion and reason are true, but the reason is not the correct explanation of the assertion.

5. **Final Answer**: The answer to the question is option 2: "Both assertion and reason are true, but reason is not the correct explanation of assertion."