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: Surgery
[{'content': "The highest concentration of potassium is in - \nSelect and explain. \nA. Plasma, B. Isotonic saline, C. Ringer lactate, D. Darrow's solution", 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Darrow's solution", 'role': 'assistant'}]