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: Pharmacology
[{'content': 'Which of the following is not an adrenergic neuron blocking drug? \nSelect and explain. \nA. Reserpine, B. Guanethidine, C. Bretylium, D. Minoxidil', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]