This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amino Acid Metabolism, Subject name: Biochemistry
[{'content': 'Coenzyme for phenylalanine hydroxylase is - \nSelect and explain. \nA. Tetrahydrofolate, B. Pyridoxal phosphate, C. S-adenosyl methionine, D. Tetrahydrobiopterin', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Tetrahydrobiopterino Phenylalanine metabolism is initiated by its oxidation to tyrosine which then undergoes oxidative degradation.", 'role': 'assistant'}]