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 matrix retainer where in anatomy adaptation is possible without wedges is: 
Select and explain. 
A. Tofflemire, B. Steele's Siqueland, C. Ivory no. 1, D. Ivory no. 8
B: Steele's Siqueland
Answer: B: Steele's Siqueland 
Explanation: None