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
[{'content': 'The indicator used in the autoclave is? \nSelect and explain. \nA. Clostridium tetani, B. Bacillus stereothermophilus, C. Bacillus pumilis, D. Bacillus subtilis Var Niger', 'role': 'user'}, {'content': "Answer: B \nExplanation: Sterilization control: for determining the efficacy of moist heat sterilization, spores of Bacillus stearothermophilus are used as the test organism. This is a thermophilic organism with an optimum growth temperature of 55-60oC and its spores require exposure of 12 minutes at 121oC to be killed REF:Ananthanarayan & Panicker's Textbook of Microbiology 8th edition pg no:34", 'role': 'assistant'}]