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': 'Fluid entering DCT is always: \nSelect and explain. \nA. Hypotonic., B. Hypertonic., C. Isotonic., D. None.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Kidney receives approx 25% of cardiac output. \nFluid entering DCT is always Hypotonic.', 'role': 'assistant'}]