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': 'Most stable amino acid at the physiological pH is \nSelect and explain. \nA. Histidine, B. Lysine, C. Arginine, D. Glycine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: As histidine titrates in the physiological pH range it remains stable.', 'role': 'assistant'}]