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: Anaesthesia
[{'content': 'Concentration of lignocaine used \nSelect and explain. \nA. 2%, B. 4%, C. 5%, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A i.e., 2% B i.e., 4% C i.e., 5%', 'role': 'assistant'}]