This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuromuscular Blocker, Subject name: Anaesthesia
[{'content': 'The first neuromuscular blocker- \nSelect and explain. \nA. Succinylcholine, B. d-tubocurare, C. Atracurium, D. Doxacurium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The first agent to be used was d-tubocurare the purified and standardized product of plant chondrodendron tomentosum.', 'role': 'assistant'}]