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': 'Tyrosine utilized in synthesis of all except ? \nSelect and explain. \nA. Melanin, B. Melatonin, C. Dopamine, D. Thyroxine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Melatonin', 'role': 'assistant'}]