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
Bias that arises from evaluating data on patients and hospital records only such that probability of exposure to a particular factor is increased is known as: 
Select and explain. 
A. Berkesonian bias, B. Confound bias, C. Memory or recall bias, D. Selection bias
A: Berkesonian bias
Answer: A: Berkesonian bias 
Explanation: None