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
Asbestos filter used for absolute sterility? 
Select and explain. 
A. HP : PYR, B. HP : EK, C. HP : EKS, D. HP : MK
C: HP : EKS
Answer: C: HP : EKS 
Explanation: None