This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Microbiology
Bacillus stearothermophilus is used as an indicator for- 
Select and explain. 
A. Hot air oven, B. Radiation, C. Gas sterilization, D. Autoclaving
D: Autoclaving
Answer: D: Autoclaving 
Explanation: Ans. is 'd' i.e., Autoclaving Type of SterilizationSpore used* Moist heat (autoclave)Bacillus stearothermophilus* Dry heat (hot air oven)Bacillius subtilis* Ionizing radiationBacillus pumilis* Gas sterilization (ethylene oxide)Bacillus subtilis* Plasma sterilizationBacillus stearothemophilus(Geobacillus stearothermophilus)