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
Which of the following drug is not used for the treatment of Alzheimer's disease: 
Select and explain. 
A. Tacrine., B. Physostigmine., C. Rivastigmine., D. Donepezil.
B: Physostigmine.
Answer: B: Physostigmine. 
Explanation: Alzhiemer's

Tacrine
Donepezil
Rivastigmine
Gallantamine