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': 'Ineffective osmols is \nSelect and explain. \nA. Na+, B. K+, C. Urea, D. All', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Some osmoles do not exert osmotic pressure as they freely cross through a membrane. These are ineffective osmoles. Eg: Urea, Glucose.', 'role': 'assistant'}]