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': 'A region is divided into 50 villages for the purpose of a survey. 10 villages are then selected randomly for the purpose of a study. This type of sampling is termed as: \nSelect and explain. \nA. Simple Random sampling, B. Stratified sampling, C. Cluster Sampling, D. Systematic Sampling', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cluster samples may be chosen where individuals fall naturally into groups or clusters. In the above scenario, a sample of the clusters is chosen at random, and then a random sample of units is chosen from within this selection of clusters. The villages are naturally formed groups or clusters in the region. Ref: Encyclopaedic Companion to Medical Statistics, Editors Brian S. Everitt and Christopher R. Palmer, Second Edition; Oxford Handbook of Medical Statistics, By Janet L. Peacock, Philip J. Peacock, Oxford University Press 2011, Page 55.', 'role': 'assistant'}]