Assertion : The protein part of the enzyme is called apoenzyme and non-protein part of the enzyme is called co-factor.
Reason : Zinc is a co-factor for the proteolytic enzyme carboxypeptidase.

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

Explanation

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 protein part of the enzyme is called apoenzyme and the non-protein part of the enzyme is called co-factor."
- This is correct. In enzymology, the protein component of an enzyme is indeed referred to as the apoenzyme, while the non-protein component, which can be a metal ion or a coenzyme, is known as the cofactor.

2. **Understanding the Reason**:
- The reason states that "Zinc is a co-factor for the proteolytic enzyme carboxypeptidase."
- This statement is also correct. Zinc acts as a cofactor for the enzyme carboxypeptidase, which is involved in protein digestion.

3. **Evaluating the Relationship**:
- While both the assertion and the reason are true, the reason does not directly explain the assertion. The assertion is a general statement about the definitions of apoenzyme and cofactor, while the reason provides a specific example of a cofactor (zinc) without linking it back to the definition of apoenzyme.

4. **Conclusion**:
- Since the assertion is correct and the reason is also correct but does not explain the assertion, the correct answer is:
**B: Assertion is correct but reason is not the correct explanation of it.**