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: Physiology
[{'content': 'Receptor for absorption of Vit-B12 intrinsic factor complex is located in \nSelect and explain. \nA. Ileum, B. Duodenum, C. Transverse colon, D. Descending colon', 'role': 'user'}, {'content': 'Answer: A \nExplanation: For the absorption of Vit B12, it has to form a complex with Intrinsic factor. This complex has a receptor on the epithelial cell surface of ileum. Once attached, the complex is absorbed.', 'role': 'assistant'}]