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: Physiology
[{'content': 'Deficiency of vasopressin results in: \nSelect and explain. \nA. Inability of the kidney to concentrating urine, B. Increased Na+ loss, C. Hyperkalemia, D. Decreased urine output', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Inability of the kidney to concentrating urine', 'role': 'assistant'}]