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': '"Type I phenylketonuria" is caused by a deficiency of \nSelect and explain. \nA. Phenylalanine transminase, B. Phenylalanine hydrolaxase, C. Tyrosine transaminase, D. Tyrosine hydroxylase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Hyperphenylalaninemias arise from defects in phenylalanine hydroxylase, EC 1.14.16.1 (type I, classic phenylketonuria (PKU), frequency 1 in 10,000 bihs), in dihydrobiopterin reductase (types II and III), or in dihydrobiopterin biosynthesis (types IV and V).Ref: Harper&;s Biochemistry; 30th edition; Chapter 29 Catabolism of the Carbon Skeletons of Amino Acids', 'role': 'assistant'}]