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': 'Interstitial fluid volume can be measure by \nSelect and explain. \nA. Tritium oxide - Sodium thiosulfate, B. Inulin - Radioactive sodium, C. Aminopyrine - Sucrose, D. Inulin - Sodium albumin labelled with radioactive Iodine.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Interstitial fluid volume cannot be calculated directly. It is measure as ECF volume. Plasma volume\nECF volume calculated by Inulin. Plasma volume calculated by Serum albumin labelled with radioactive Iodine.', 'role': 'assistant'}]