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
Step back technique is consist of: 
Select and explain. 
A. 2 phases., B. 3 phases., C. 4 phases., D. None.
A: 2 phases.
Answer: A: 2 phases. 
Explanation: step back technique has 2 phases.
Phase 1 is apical preparation phase.
Phase 2 stepping back phase.