This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology metabolism, Subject name: Physiology
[{'content': 'Active form of Vitamin D3 is: \nSelect and explain. \nA. Calcitriol, B. Calciferol, C. Calcidiol, D. Ergocalciferol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A CalcitriolRef: Ganong, 25th ed. pg. 378The active metabolite of vitamin D3 is produced in kidney and is called calcitriol or 1,25 dihyroxycholecalciferol. The cells of proximal convoluted tubule produce an enzyme by name of 1 alpha hydroxylase that converts 25 hydroxycholecalciferol into 1,25 dihyroxycholecalciferol.', 'role': 'assistant'}]