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: Dental
For large country surveys the sampling method of choice is: 
Select and explain. 
A. Multiple sampling, B. Multiphase sampling, C. Cluster sampling, D. Multistage random sampling
D: Multistage random sampling
Answer: D: Multistage random sampling 
Explanation: None