This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Digestion and Absorption, Subject name: Physiology
[{'content': 'Intrinsic factor is required for absorption of - \nSelect and explain. \nA. Folic acid, B. Vitamin B12, C. Vitamin B2, D. Vitamin B6', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Vitamin B12 o Vitamin B12 (cyanocobalamine) is absorbed in the ileum, o Intrinsic factor (of castle) is necessary for its absorption. o IF is secreted by oxyntic cells of stomach. In the lumen of the small intestine, IF forms a complex with vitamin B12. o Vitamin B12-IF complex binds with a specific receptor on the surface of the epithelial cells of the ileum. o Vitamin B12 is transported into the enterocytes leaving behing IF at the brush border.", 'role': 'assistant'}]