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 drugs is most effective for control of orthostatic hypotension: 
Select and explain. 
A. Clonidine, B. Fludrocortisone, C. Esmolol, D. Phenylephrine
B: Fludrocortisone
Answer: B: Fludrocortisone 
Explanation: None