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': 'Juxtamedullary nephrons in kidney are what percentage of total nephrons \nSelect and explain. \nA. 15, B. 50, C. 70, D. 90', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. 15%', 'role': 'assistant'}]