This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Minerals, Subject name: Biochemistry
[{'content': 'Most potent form of vitamin D is: \nSelect and explain. \nA. 1, 25- dihydroxy cholecalciferol, B. 7-dihydro cholecalciferol, C. 25-hydroxy cholecalciferol, D. Ergocalciferol (Vit. D2)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Vitamin D Ergocalciferol (Vitamin D2) =Formed from ergosterol and cholecalciferol (vitamin D3) and are known as Pro-vitamins =Vitamins D2and D3 are not biologically active. 25-OH- cholecalciferol =Major storage and circulating form of vitamin D 1, 25 dihydroxycholecalciferol =aka Calcitriol =most biologically active form of vitamin D Vitamin D encompasses a group of sterols, which have a hormone-like function. Bioactive vitamin D or calcitriol is a steroid hormone that has long been known for its impoant role in regulating body levels of calcium and phosphorus, and in mineralization of bone.', 'role': 'assistant'}]