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': 'According to the International Organization for Standards (ISO) refinements 3950 to the FDI system, 05 refers to: \nSelect and explain. \nA. Upper right sextant, B. Upper left sextant, C. Lower right sextant, D. Lower left sextant', 'role': 'user'}, {'content': "Answer: B \nExplanation: International Organization for Standards (ISO) has added refinements (ISO 3950) to the FDI system to designate areas of the oral cavity and to provide 'sextants' as with the CPITN.\xa0\n00 whole oral cavity\xa0\n01 maxillary area\xa0\n02 mandibular area\xa0\n03 upper right sextant\xa0\n04 upper anterior sextant\xa0\n05 upper left sextant\xa0\n06 lower left sextant\xa0\n07 lower anterior sextant\xa0\n08 lower right sextant\xa0\n09 additional document", 'role': 'assistant'}]