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
[{'content': 'Which sampling method is used in pathfinder surveys? \nSelect and explain. \nA. Simple random, B. Stratified random, C. Stratified cluster, D. Snowball', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]