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': 'Vitamin deficiency associated with increase xanthurenic acid excretion in urine \nSelect and explain. \nA. Thiamine, B. Pyridoxine, C. Ascorbic acid, D. Niacin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]