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': 'Sterilization accuracy is assessed by using: \nSelect and explain. \nA. Clostridium perfringenes, B. Geobacillus stereothermophilus, C. Staphylococcus aureus, D. Clostridium botulinum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Geobacillus stereothermophilus and Bacillus subtilis subsp. Niger are used as biological indicators in sterilization.', 'role': 'assistant'}]