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
Which of the following blade angle is appropriate for scaling and root planing 
Select and explain. 
A. A, B. B, C. C, D. D
B: B
Answer: B: B 
Explanation: Blade angulation.
(A) 0 degrees: correct angulation for blade insertion.
(B) 45 to 90 degrees: correct angulation for scaling and root planing.
(C) less than 45 degrees: incorrect angulation for scaling and root planing.
(d) More than 90 degrees: incorrect angulation for scaling and root planing, but correct angulation for gingival curettage.