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
Perforated trays are used with 
Select and explain. 
A. Alginate impression material, B. Silicone impression material, C. Modeling compound, D. Impression waxes
A: Alginate impression material
Answer: A: Alginate impression material 
Explanation: Perforated trays are used for alginate impression material to mechanically hold the impression in tray with the help of perforations.