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: Medicine
[{'content': 'Vitamin B12 is required for a number of metabolic processes. Which of the following lesions would NOT lead to a deficiency of this vitamin? \nSelect and explain. \nA. Chronic gastritis resulting in achlorhydria, B. Autoimmune destruction of gastric parietal cells, C. Surgical resection of the jejunum, D. Surgical resection of the ileum', 'role': 'user'}, {'content': "Answer: C \nExplanation: Absorption of vitamin B12 requires formation of a complex with intrinsic factor, which is secreted by parietal cells of the stomach. Destruction of these cells thus results in a vitamin B12 deficiency. The vitamin B12-intrinsic factor complex is absorbed in the ileum. Thus, surgical resection of the ileum, but not of the jejunum, will also produce a deficiency. Ref: Kaushansky K., Kipps T.J. (2011). Chapter 37. Hematopoietic Agents: Growth Factors, Minerals, and Vitamins. In L.L. Brunton, B.A. Chabner, B.C. Knollmann (Eds), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e.", 'role': 'assistant'}]