This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine System, Subject name: Physiology
[{'content': 'Active form of vitamin D is: \nSelect and explain. \nA. Calcitriol, B. Calcifediol, C. Cholecalciferol, D. Ergocalciferol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 1,25-dihydroxycholecalciferol or calcitriol is the active form of Vit-D .', 'role': 'assistant'}]