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': 'The strip technique which is a variant of free gingival graft was developed by \nSelect and explain. \nA. Rateit-Schak et.al, B. Han et.al, C. Edel et.al, D. Bjorn et.al', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]