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': 'Sampling error is classified as - \nSelect and explain. \nA. Alpha error, B. Beta error, C. Gamma error, D. Delta error', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]