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': 'Which of the following local anaesthetic agent is a vasoconstrictor \nSelect and explain. \nA. Lignocaine, B. Cocaine, C. Bupivacaine, D. Tetracaine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cocaine is sympathomimetic agent.', 'role': 'assistant'}]