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 offset angle of Gracey curette between the blade and shank is: 
Select and explain. 
A. 50°, B. 70°, C. 80°, D. 90°
B: 70°
Answer: B: 70° 
Explanation: None