This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
[{'content': 'Nitric Oxide synthesised from: \nSelect and explain. \nA. Arginine, B. Citrulline, C. Alanine, D. Cysteine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. ArginineSynthesis of Nitric Oxide', 'role': 'assistant'}]