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: Social & Preventive Medicine
Physiologically most active form of Vitamin D is 
Select and explain. 
A. Calciferol, B. Calcitriol, C. Ergocalciferol, D. Cholecalciferol
B: Calcitriol
Answer: B: Calcitriol 
Explanation: None