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': 'Which of the following will cause an increase in the prevalence of the disease- \nSelect and explain. \nA. Immigration of healthy persons, B. Increased cure rate of the disease, C. Longer duration of disease, D. Emigration of diseased persons', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref:Parks 23rd edition pg 62 Change in prevalence from one time to another can result from changes in: Incidence Duration of disease Or both', 'role': 'assistant'}]