This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Which of the following is metabolically active form of Vitamin D \nSelect and explain. \nA. Cholecalciferol, B. 25 hydroxy vit D, C. 1, 25 dihydroxy Vit D, D. 24, 25 dihydroxy Vit D', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]