This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Preoperative assessment and monitoring in anaesthesia, Subject name: Anaesthesia
[{'content': 'Amount of K+ in ringer lactate is \nSelect and explain. \nA. 2, B. 4, C. 5, D. 6', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ringer lactate solution include a concentration of 4mEq/L.', 'role': 'assistant'}]