This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
[{'content': 'All of the following are used to measure ECF volume, except \nSelect and explain. \nA. Sucrose, B. Sodium chloride, C. Inulin, D. Heavy water', 'role': 'user'}, {'content': 'Answer: B \nExplanation: ECF is measured using inulin which is a polysaccharide. Other substances used are mannitol and sucrose. These substances cannot enter a cell but can freely cross the capillary membrane and thus distribute evenly in the ECF compaments. (REF: TEXTBOOK OF MEDICAL PHYSIOLOGY GEETHA N 2 EDITION, PAGE NO - 61)', 'role': 'assistant'}]