This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'True about Rx of Phenylketonuria \nSelect and explain. \nA. Limiting the substrate for deficient enzyme, B. Giving the missing amino acids by diet, C. Gene therapy can be successfully used, D. Child should refrain from milk.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]