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
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- 
Select and explain. 
A. Simple random sampling, B. Stratified sampling, C. Cluster sampling, D. Systematic sampling
C: Cluster sampling
Answer: C: Cluster sampling 
Explanation: .