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
[{'content': 'Which is the amino acid shown below \nSelect and explain. \nA. Histidine, B. Proline, C. Phenylalanine, D. Tyrosine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Proline is an imino acid, because it has an imino group (=NH) instead of amino group (-NH2).\nThe ring structure present in proline in known as pyrrolidine ring.', 'role': 'assistant'}]