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': 'Advent of Electrolytic etching of base metal paved a path for development of \nSelect and explain. \nA. Cast perforated resin bonded fixed dental prosthesis, B. Maryland Bridge, C. Rochette Bridge, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A technique for the electrolytic etching of cast base metal\xa0\xa0retainers\xa0was\xa0developed at the University of Maryland by\xa0\xa0\n\n\nThompson\xa0 and\xa0\xa0Livaditis.\xa0 Etched-cast\xa0 retainers\xa0 have\xa0\xa0\xa0definite advantages\xa0over cast-perforated restorations:\xa0\n\n\n\nRetention is improved because the resin-to-etched metal bond can be substantially stronger than the\xa0resin-to-etched\xa0 enamel.\xa0\xa0The\xa0 retainers\xa0 can\xa0 be thinner yet still resist flexing.\xa0\n\n\n\n\nThe oral surface of the cast retainers is highly polished and resists plaque accumulation.', 'role': 'assistant'}]