This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anesthesia, Subject name: Pharmacology
[{'content': 'Muscle relaxant of choice in renal and hepatic failure \nSelect and explain. \nA. Cis Atracurium, B. Vecuronium, C. Rocuronium, D. Rapacuronium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Refer Katzung 9/e p432 Atracurium and cis-Atracurium are muscle relaxants of choice for renal and hepatic failure patients', 'role': 'assistant'}]