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
Disadvantage of cast perforated resin retained fpd is 
Select and explain. 
A. Weakening of metal retainer, B. Wear of resin at perforation, C. Less adhesion, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Disadvantage:

Weakening of the metal retainer by the perforations.
Exposure to wear of the resin at the perforations.
Limited adhesion of the metal provided by the perforations.