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': 'Standard error of mean is calculated by \nSelect and explain. \nA. SD/n, B. SD/mean, C. SD/-1/1, D. Mean/SD', 'role': 'user'}, {'content': 'Answer: C \nExplanation: SD/ 1/7 Standard error of mean = SD/j SD - standard detion n - number of samples', 'role': 'assistant'}]