This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
[{'content': 'Selenocysteine is synthesized from \nSelect and explain. \nA. Alamine, B. Cysteine, C. Arginine, D. Histidine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Selenocysteine is the 21st amino acid. Biosynthesis of Selenocysteine is by replacing the oxygen by selenium in Serine which in turn formed from Cysteine.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 214', 'role': 'assistant'}]