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
Most common problem faced with single etch adhesive system is 
Select and explain. 
A. Phase Separation, B. Technique Sensitive, C. Collagen Fiber Collapse, D. Increased Viscosity
A: Phase Separation
Answer: A: Phase Separation 
Explanation: None