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: Social & Preventive Medicine
[{'content': 'All of the following statements regarding prevalence are true except \nSelect and explain. \nA. It is proportion, B. Duration of disease effects prevalence, C. Numerator is a part of denominator, D. It is rate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Prevalence is a proportion with numerator being a part of denominator.\nPrevalence refers specifically to all current cases (old and new) existing at a given point in time, or over a period of time in a given population.', 'role': 'assistant'}]