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: Microbiology
Sterilisation is 
Select and explain. 
A. Pathogens killed but spores are not affected, B. Only pathogenic micro-organisms killed, C. Non-pathogenic killed, D. All pathogenic and non-pathogenic microorganisms killed
D: All pathogenic and non-pathogenic microorganisms killed
Answer: D: All pathogenic and non-pathogenic microorganisms killed 
Explanation: None