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
Which of the following is metabolically active form of Vitamin D 
Select and explain. 
A. Cholecalciferol, B. 25 hydroxy vit D, C. 1, 25 dihydroxy Vit D, D. 24, 25 dihydroxy Vit D
C: 1, 25 dihydroxy Vit D
Answer: C: 1, 25 dihydroxy Vit D 
Explanation: None