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: Microbiology
[{'content': 'Botulin toxin acts by: \nSelect and explain. \nA. Decreases Secretion of Ach, B. Decreases Synthesis of Ach, C. Muscle nerve block, D. Inhibits Ach release', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Decreases Secretion of Ach', 'role': 'assistant'}]