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: Unknown
[{'content': 'Branched-chain ketoacid decarboxylation is defective in - \nSelect and explain. \nA. Maple syrup urine disease, B. Hartnup disease, C. Alkaptonuria, D. GM-1 gangliosidosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans-A', 'role': 'assistant'}]