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': 'In a population sample size depends on \nSelect and explain. \nA. expected prevalence, B. expected incidence, C. universe size, D. population size', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]