This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
Zn is present as prosthetic group in this enzyme: 
Select and explain. 
A. Carbonic anhydrase, B. Carboxy peptidase, C. Lactate dehydrogenase, D. All of these
D: All of these
Answer: D: All of these 
Explanation: Ans. D. All of theseAll enzymes are proteins. It consists of a protein part and a non-protein part. If a non-protein part is a metal ion it becomes a co-factor. If a non-protein part is an organic molecule it becomes a co-enzyme. Zinc is a co factor of so many biochemical reactions.