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': 'Water irrigating devices are most useful in \nSelect and explain. \nA. Removing plaque, B. Preventing plaque formation, C. Diluting bacterial products, D. Reducing periodontal pockets', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]