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': 'Which type of Bacillus is used to test efficacy of Sterilisation by Autoclave? \nSelect and explain. \nA. Bacillus subtilis, B. Bacillus pumilis, C. Bacillus stearothermophilus, D. Coxiella burnetti', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Sterility indicator strips containing spores from the bacterium Bacillus stearothermophilus is used to test efficacy of sterilisation by autocalving. It is a thermophilic bacterium with an optimum temperature of 55-60 degree celsius and its spores require an exposure of 12minutes at 121 degree celsius to die. Spores of Clostridium tetani are used as sterilization controls to determine the efficacy of sterilization by hot air oven.', 'role': 'assistant'}]