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
[{'content': 'Most common problem faced with single etch adhesive system is \nSelect and explain. \nA. Phase Separation, B. Technique Sensitive, C. Collagen Fiber Collapse, D. Increased Viscosity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]