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
Impression material which has a high incidence of air porosity is 
Select and explain. 
A. Alginate impression material, B. Impression compound, C. Zinc oxide eugenol impression paste, D. Polyether impression material
A: Alginate impression material
Answer: A: Alginate impression material 
Explanation: None