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': 'Concentration of sodium in ECF is \nSelect and explain. \nA. 130-136 millimoles/lit, B. 132-140 millimoles/lit, C. 138-146 millimoles/lit, D. 140-147 millimoles/lit', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Sodium levels are usually between 136to 145 mmol/L . Blood sodium level less than 136mmol/L mean you have less sodium Ref:Guyton and Hall textbook of medical physiology 12th edition,page number: 50', 'role': 'assistant'}]