This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
All are physical methods of sterilisation except 
Select and explain. 
A. Sunlight, B. Gases, C. Filtration, D. Heat
B: Gases
Answer: B: Gases 
Explanation: Physical Methods of SterilizationHeatRadiationFiltration Chemical Methods of Sterilization: using toxic gasses Ex: ETO, Formalin gas Ref : Ananthanarayana textbook of Microbiology 9th edition Pgno : 33