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': 'Earliest (first) L.A. used clinically \nSelect and explain. \nA. Xylocaine/Lidocaine, B. Morphine, C. Cocaine, D. Cannabis & Procaine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Cocaine', 'role': 'assistant'}]