This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amino Acid Metabolic Disorder, Subject name: Biochemistry
[{'content': 'Phenylketonuria is due to deficiency of - \nSelect and explain. \nA. Phenylalanine transaminase, B. Phenylalanine hydroxylase, C. Tyrosine transaminase, D. Tyrosine hydroxylase', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Phenylalanine hydroxylase o Repeat from previous session", 'role': 'assistant'}]