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
All of the following holds true about cluster sampling, except: 
Select and explain. 
A. Is a Rapid and simple method, B. Samples are similar to those in Simple Random Sampling, C. It is a type of probability sample, D. The sample size may vary according to study design
B: Samples are similar to those in Simple Random Sampling
Answer: B: Samples are similar to those in Simple Random Sampling 
Explanation: Cluster sampling is entirely different from Random sampling. The following are differences between random sampling and cluster sampling. Ref: Park's Texbook of Preventive and Social Medicine 19th Edition; Pages 702; High Yield Biostatistics by Anthony N. Glaser 2nd Edition, Pages 2 -3; Methods in Biostatistics By Mahajan6th Edition, Pages 96 - 100; Sampling of Populations: Methods and Applications By Paul S. Levy, Stanley Lemeshow 4th Edition; Pages 269 - 272; 223 - 229.