This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Regional Anesthesia, Subject name: Anaesthesia
[{'content': 'Which of the following local anaesthetic causes least vasodilation: \nSelect and explain. \nA. Bupivacaine, B. Prilocaine, C. Ropivacaine, D. Lignocaine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Prilocaine causes less vasodilation than other local anesthetics and thus used without using epinephrine added to the local anesthetic solution.', 'role': 'assistant'}]