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
What is the minimum amount of taper that should be maintained for an ideal tooth preparation: 
Select and explain. 
A. 4 degree, B. 5 degree, C. 6 degree, D. 12 degree
D: 12 degree
Answer: D: 12 degree 
Explanation: None