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 most preferred type of Dental floss is: \nSelect and explain. \nA. Unwaxed thin floss, B. Unwaxed thick floss, C. Waxed thin floss, D. Waxed thick floss', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]