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
Agar polymer has 
Select and explain. 
A. Brush heap structure, B. Interdigitation structure, C. Fish belly structure, D. All of the above
A: Brush heap structure
Answer: A: Brush heap structure 
Explanation: Composition of Commercial Reversible Hydrocolloid Impression Materials: