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': 'Which of the following is not synthesised from tyrosine? \nSelect and explain. \nA. Nor epinephrine, B. Melatonin, C. Thyroxine, D. Dopamine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]