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': 'Phenylalanemia I is due to deficiency of ? \nSelect and explain. \nA. Phenylalanine hydroxylase, B. Homogentisate oxidase, C. Tyrosinase, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Phenylalanine hydroxylase i) Classical phenylketonuria (hyperphenylalanemia type I) Deficiency of phenylalanine hydroxylase.ii) Atypical phenylketonuria (hyperphenylalanemia type II and III) * Defect in dihydrobiopterin reductase.iii) Hyperphenylalanemia type IV and V * Defect in dihydrobiopterin synthesis.', 'role': 'assistant'}]