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': 'Which one of the following combination is wrong? \nSelect and explain. \nA. Phenylalanine - Niacin, B. Trytophon - Serotonin, C. Phenylalanine - Melanin, D. Tyrosine - Epinephrine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Niacin is formed by metabolism of tryptophan. Other options are correct amino acids and their metabolic productsRef: Textbook of biochemistry for medical students, seventh edition, page no: 239', 'role': 'assistant'}]