This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
[{'content': 'Botulinum affects all except: \nSelect and explain. \nA. Neuromuscular junction, B. Preganglionic junction, C. Post ganglionic nerves, D. CNS', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., CNS(Ref: Harrison, 18th/e, p. 1200 and 17th/e, p. 901)* The central nervous system is not involved because the toxin does not cross the blood brain barrier.", 'role': 'assistant'}]