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
The retainerless matrix system with four types of bands fitted around any teeth regardless of its circumference is called 
Select and explain. 
A. Tofflemire matrix, B. Auto matrix, C. Ivory No. 1 matrix, D. Ivory No. 8 matrix
B: Auto matrix
Answer: B: Auto matrix 
Explanation: None