This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'Normal plasma osmolality in mOsmol/kg H2O \nSelect and explain. \nA. 290, B. 385, C. 485, D. 585', 'role': 'user'}, {'content': "Answer: A \nExplanation: The osmolarity is the number of osmoles per litre of solution The freezing point of normal human plasma averages -0.54 degC, which corresponds to an osmolal concentration in plasma of 290 mOsm/L Ref: Ganong's Review of Medical Physiology Twenty-Third Edition Page No:6", 'role': 'assistant'}]