This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
Organs take pa in vitamin D formation 
Select and explain. 
A. Liver, B. Skin, C. Kidney, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Vitamin D is formed in skin with help of sunlight and activated in liver and kidneyRef: Ganong&;s review of medical physiology; 24th edition; page no: 380