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 force applied to cause root movement should be 
Select and explain. 
A. Positive intermittent force, B. Torque or moment, C. Extra - oral, D. Gentle action
B: Torque or moment
Answer: B: Torque or moment 
Explanation: None