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
Which material is carried in a custom tray? 
Select and explain. 
A. High fusing compound, B. Reversible hydrocolloid, C. Metallic oxide paste, D. Irreversible hydrocolloid
C: Metallic oxide paste
Answer: C: Metallic oxide paste 
Explanation: None