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 naturally occurring tertiary amine and lipid-soluble reversible anticholinesterases: \nSelect and explain. \nA. Physostigmine., B. Neostigmine., C. Pyridostigmine., D. All of the above.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: All other reversible anticholinesterases are synthetic quaternary compounds and are lipid insoluble.', 'role': 'assistant'}]