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 disadvantage of winged rubber dam retainer is that it interferes with the placement of \nSelect and explain. \nA. Matrix bands, B. Dental floss, C. Rubber dam frame, D. Rubber dam sheet', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]