This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidneys and Body Fluids, Subject name: Physiology
[{'content': '25(OH) cholecalciferol is converted to 1,25-dihydroxy - cholecalciferol in: \nSelect and explain. \nA. Skin, B. Lung, C. Liver, D. Kidney', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D KidneyRef: Ganong, 23rd ed. pg. 674', 'role': 'assistant'}]