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': 'Long term fluctuation is seen with \nSelect and explain. \nA. secular trends, B. epidemics, C. cyclic trends, D. seasonal trends', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]