This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
[{'content': 'Tryptophan gives rise to \nSelect and explain. \nA. Thyroxine, B. Melatonin, C. Melanin, D. Epinephrine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Melatonin is synthesised from serotonin which in turn is from tryptophan.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 519', 'role': 'assistant'}]