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: Surgery
[{'content': 'Arrange the following long acting LA in descending order of their duration of action. \nSelect and explain. \nA. Dibucaine>Etidocaine>Tetracaine> Bupivacaine., B. Dibucaine>Tetracaine>Bupivacaine> Etidocaine., C. Tetracaine>Dibucaine>Bupivacaine>Etidocaine., D. Tetracaine>Bupivacaine>Dibucaine> Etidocaine.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Dibucaine is longest acting and most toxic.\nEtidocaine: 200minutes.\nTetracaine~Bupivacaine:175 minutes.', 'role': 'assistant'}]