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
A sampling unit is defined as 
Select and explain. 
A. A group of sample, B. A subset of sample, C. Representing every member of sample, D. All of the above
C: Representing every member of sample
Answer: C: Representing every member of sample 
Explanation: None