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: Anatomy
[{'content': 'Submucosal glands are present in the following pa of gastro intestinal tract: \nSelect and explain. \nA. Duodenum, B. Colon, C. Anal canal, D. Stomach', 'role': 'user'}, {'content': "Answer: A \nExplanation: The major distinguishing feature of this C-shaped first pa of the small intestine duodenum) is the presence of duodenal (Brunner's) glands in the submucosa. The mucous cells of these glands produce an alkaline secretion (pH 8.1-9.3) that enters the lumen through the crypts. It protects the duodenal lining from the acidity of the chyme and raises the luminal pH to optimize pancreatic enzyme activity. Ref: Paulsen D.F. (2010). Chapter 15. Digestive Tract. In D.F. Paulsen (Ed), Histology & Cell Biology: Examination & Board Review, 5e.", 'role': 'assistant'}]