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
When treating hypertension chronically, orthostatic hypotension is maximum with: 
Select and explain. 
A. Clonidine, B. Guanethidine, C. Prazosin, D. Propranolol
B: Guanethidine
Answer: B: Guanethidine 
Explanation: None