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': 'Which of following is not a permanent mucosal fold? \nSelect and explain. \nA. Spiral valve of Heister, B. Gastric rugae, C. Plica circularis, D. Transverse rectal fold', 'role': 'user'}, {'content': "Answer: B \nExplanation: Gastric rugae of the stomach and longitudinal folds in the mucosa of upper rectum and colon are temporary mucosal folds and are obliterated by distension. Whereas, plica circularis of the small intestine, crescentic mucosal folds of cystic duct (spiral valve of Heister), transverse (horizontal) rectal folds (Houston's valves or plica transversalis) and permanent longitudinal rectal columns or folds (found in the lower rectum and anal canal)\xa0are permanent mucosal folds.", 'role': 'assistant'}]