This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Ouabain acts by inhibiting: 
Select and explain. 
A. Adenyl cyclase, B. Ca++ channels, C. H+K+ ATPase, D. Na+K+ ATPase
D: Na+K+ ATPase
Answer: D: Na+K+ ATPase 
Explanation: Ref:KDT 6/e p496