This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'Calculate the prevalence if incidence is 2 cases per 1,000 population per year and mean duration is 4 years- \nSelect and explain. \nA. 8 mases per 1,000 population, B. 2 cases per 1,000 population, C. 0.5 cases per 1,000 population, D. 32 cases per 1,000 population', 'role': 'user'}, {'content': 'Answer: A \nExplanation: prevalence is calculated as the product of incidence and mean duration of a disease in a community.during a specific period,here it is given as 4 *2 cases per 1000 population. ref:park&;s textbook,ed 22,pg no 67', 'role': 'assistant'}]