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
The process by which controls are selected in such a way that they are similar to cases with regard to certain clinical variables in a case control study is known as 
Select and explain. 
A. Confounding, B. Matching, C. Bias, D. Sampling
B: Matching
Answer: B: Matching 
Explanation: None