This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
[{'content': 'Vasopressin antagonist acts on \nSelect and explain. \nA. Proximal convoluted tubule, B. Distal convoluted tubule, C. Coical collecting tubule, D. Medullary collecting duct', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Vaspression receptors(V2) are present on principal cells of inner medullary collecting tubule. The antagonist like Conivaptan and Tolvaptan may be used in conditions like SIADH and CHF.', 'role': 'assistant'}]