This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal System, Subject name: Physiology
[{'content': "Brunner's glands are seen in: \nSelect and explain. \nA. Jejunum, B. Upper duodenum, C. Lower duodenum, D. Appendix", 'role': 'user'}, {'content': "Answer: B \nExplanation: An extensive array of compound mucous glands, called Brunner's glands, is located in the submucosa of the first few centimeters of the duodenum, mainly between the pylorus of the stomach and the papilla of Vater These glands secrete large amounts of alkaline (pH 9) mucus.", 'role': 'assistant'}]