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
This type of tray is used for taking impression of: 
Select and explain. 
A. Extremely resorbed ridges, B. Restricted mouth opening cases, C. Flabby ridges, D. In patients with severe gag reflex
C: Flabby ridges
Answer: C: Flabby ridges 
Explanation: This tray is made by using window technique and is used for taking impression of ﬂabby ridges. Flabby tissue is recorded using mucostatic material like low viscosity elastomers.