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 wherein anatomy adaptation is possible without wedges is \nSelect and explain. \nA. Tofflemire, B. Steele’s siqveland, C. Ivory no. 1, D. Ivory no. 8', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Steele’s Siqveland is a self- adjusting matrix retainer without the use of wedges. It is used on a tapering tooth.', 'role': 'assistant'}]