input: The following are multiple choice questions (with answers) about medical knowledge.   **Question:** A routine newborn screening test for phenylketonuria in a male neonate shows a serum phenylalanine concentration of 44 mg/dL (N < 20). He is started on a special diet and the hyperphenylalaninemia resolves. At a routine well-child examination 4 months later, the physician notices that he has persistent head lag. On examination, he has blue eyes, pale skin, blonde hair, and generalized hypotonia. His serum prolactin level is markedly elevated. Supplementation of which of the following substances is most likely to prevent further complications of this patient's condition?   (A) Tyrosine   (B) Pyridoxine   (C) Thiamine   (D) Tetrahydrobiopterin
output: ['(D) Tetrahydrobiopterin <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Tyrosine  (B) Pyridoxine  (C) Thiamine  (D) Tetrahydrobiopterin <> possible answers', "  A routine newborn screening test for phenylketonuria in a male neonate shows a serum phenylalanine concentration of 44 mg/dL (N < 20). He is started on a special diet and the hyperphenylalaninemia resolves. At a routine well-child examination 4 months later, the physician notices that he has persistent head lag. On examination, he has blue eyes, pale skin, blonde hair, and generalized hypotonia. His serum prolactin level is markedly elevated. Supplementation of which of the following substances is most likely to prevent further complications of this patient's condition? <> context"]