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
[{'content': 'Bacillus used to test the efficacy of Sterilization by Autoclave is? \nSelect and explain. \nA. Bacillus subtilis., B. Bacillus pumilus, C. Bacillus stearothermophilus, D. Coxiella burnetii', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Various bacilli are used to check the efficacy of sterilization methods are:\n\nAutoclave- Bacillus stearothermophilus\nHot air oven- Bacillus subtilis subspecies niger\nIonising radiation- Bacillus pumilus', 'role': 'assistant'}]