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': 'One of the following adjunctive aids, necessary to check\non the efficacy of oral prophylaxis for young patient \nSelect and explain. \nA. Disclosing solution, B. Sandpaper strip, C. Synder test, D. Unwaxed floss', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]