This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
The amino acid residue having iminoside chain is? 
Select and explain. 
A. Lysine, B. Arginine, C. Tyrosine, D. Proline
D: Proline
Answer: D: Proline 
Explanation: The side chain of proline makes pyrrolidine ring structure with imino group.