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
[{'content': 'Ouabain acts by inhibiting: \nSelect and explain. \nA. Adenyl cyclase, B. Ca++ channels, C. H+K+ ATPase, D. Na+K+ ATPase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref:KDT 6/e p496', 'role': 'assistant'}]