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': 'Conc. of Lidocaine used in spinal anesthesia \nSelect and explain. \nA. 5%, B. 3%, C. 2%, D. 1%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. 5%', 'role': 'assistant'}]