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': 'Central muscle relaxants act by : \nSelect and explain. \nA. Decreasing nerve conduction, B. Inhibiting spinal polysynaptic reflexes, C. Blocking conduction across NM junction, D. Causing CNS depression', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]