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 ultimate in finish Lines that permit an acute margin of metal is 
Select and explain. 
A. Shoulder, B. Chamfer, C. Knife edge, D. Shoulder with bevel
C: Knife edge
Answer: C: Knife edge 
Explanation: None