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': 'Universal matrix band retainer is also known as \nSelect and explain. \nA. Ivory 8 retainer, B. ToffLemke retainer, C. Sequiland retainer, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]