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 matrix retainer where in anatomy adaptation is possible without wedges is: \nSelect and explain. \nA. Tofflemire, B. Steele's Siqueland, C. Ivory no. 1, D. Ivory no. 8", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]