This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostats, Subject name: Social & Preventive Medicine
[{'content': "The mean of the 25 patients' plasma volumes is 12.5 litres. Standard detion is 0.25. Calculate standard error \nSelect and explain. \nA. 0.05, B. 0.5, C. 0.01, D. 0.1", 'role': 'user'}, {'content': 'Answer: A \nExplanation: S.E = S/[?]n S = Standard detion = 0.25 n = sample size = 25 S.E. = 0.25/[?] 25 = 0.25/5 = 0.05', 'role': 'assistant'}]