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': 'Disadvantage of cast perforated resin retained fpd is \nSelect and explain. \nA. Weakening of metal retainer, B. Wear of resin at perforation, C. Less adhesion, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Disadvantage:\n\nWeakening of the metal retainer by the perforations.\nExposure to wear of the resin at the perforations.\nLimited adhesion of the metal provided by the perforations.', 'role': 'assistant'}]