This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
[{'content': 'All are true about cluster sampling except? \nSelect and explain. \nA. Sample size is same as that of simple random sampling, B. It is a two stage sampling, C. It is cheapter than other methods of sampling, D. It has a disadvantage of higher sampling error', 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]