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': 'Example of asymmetric mixed-onium chlorofumarate is: \nSelect and explain. \nA. Rocuronium, B. Vecuronium, C. Gantacurium, D. Atracurium', 'role': 'user'}, {'content': "Answer: C \nExplanation: Gantacurium represents a new class of nondepolarizing neuromuscular blockers called asymmetric mixed-onium chlorofumarates. Ref: Miller's anesthesia-7th ed , Chapter 29.", 'role': 'assistant'}]