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': 'Prevalence of a disease is: \nSelect and explain. \nA. Rate, B. Ratio, C. Proportion, D. Deviation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]