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': "Dean's shoe leather survey Comes under: \nSelect and explain. \nA. Demonstration phase., B. Clinical discovery phase., C. Epidemiological phase., D. Clinical trial phase.", 'role': 'user'}, {'content': 'Answer: C \nExplanation: The history of community water fluoridation is categorized into four separate periods or phases.', 'role': 'assistant'}]