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': 'Botulinum toxin act by: \nSelect and explain. \nA. Synthesis of Ach., B. inhibits Ach release., C. Secretion of Ach., D. None of the above.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]