This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inborn Errors of Metabolism, Subject name: Pediatrics
[{'content': "Darkening of urine on standing is associated with: \nSelect and explain. \nA. Alkaptonuria, B. Cystinuria, C. Fabry's disease, D. Tyrosinemia", 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Alkaptonuria(Ref: Nelson's 20/e p 636-642, Ghai 8/e p 653-655)Darkening of urine on standing is associated with Alkaptonuria, due to Homogentisic acid oxidase deficiency.", 'role': 'assistant'}]