Indicate which of the following conditions represents an active enzyme.
I. An enzyme after its release of Cu (I) ion used for catalytic activity. 
II. A polypeptide chain that is biologically functional. 
III. An enzyme that binds to organic factor in the form of Vitamin B₂.
IV. None of the following

• A. IV only
• B. I and II
• C. II and III
• D. I, II and III

Answer: (C)

Verified step by step guidance

1. Understand that enzymes are biological catalysts that speed up chemical reactions in living organisms. They require specific conditions to be active.
2. Consider condition I: An enzyme after its release of Cu (I) ion used for catalytic activity. This suggests the enzyme has completed its catalytic function and may not be active anymore.
3. Consider condition II: A polypeptide chain that is biologically functional. This indicates that the enzyme is in its active form, as enzymes are typically functional polypeptide chains.
4. Consider condition III: An enzyme that binds to an organic factor in the form of Vitamin B2. This suggests the enzyme is active, as many enzymes require cofactors like vitamins to be functional.
5. Evaluate the conditions: II and III both describe scenarios where the enzyme is active, while I suggests post-catalytic activity, and IV states none are active, which is incorrect given II and III.