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: Dental
[{'content': 'Median palatal suture is a relief area while making upper edentulous impression  because: \nSelect and explain. \nA. It overlies nerves and vessels, B. This area is prone for resorption, C. Overlying mucous membrane is thick, D. The submucosal layer is extremely thin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Maxilla\n\nSupporting structures\n\nHard palate—rugae\nResidual alveolar ridge—maxillary tuberosity\n\n\nLimiting structures\xa0\n\nLabial frenum\nLabial vestibule\nBuccal frenum\nBuccal vestibule\nHamular notch\nFovea palatine\nPosterior palatal seal area\n\n\nRelief area:\n\nMidpalatine suture\nIncisive papilla\nTorus palatinus\n\n\nStress-bearing areas \n\nPrimary\nHorizontal slopes of hard palate lateral to\nMedian sutures\nSecondary\nCrest of the residual alveolar ridge\nRugae\nMaxillary tuberosity', 'role': 'assistant'}]