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 synthetic sterioid shows predominantly mineralocorticoid action? 
Select and explain. 
A. Hydrocortisone, B. Spironolactone, C. Dexamethsone, D. Fludrocortisone
D: Fludrocortisone
Answer: D: Fludrocortisone 
Explanation: None