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
Retainer less matrix that can be used for all teeth (Retainer less matrix) 
Select and explain. 
A. Tofflemeir, B. Ivory No.1, C. Universal, D. Automatrix
D: Automatrix
Answer: D: Automatrix 
Explanation: None