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': 'Spore of which bacteria is used as sterilization control of Plasma sterilization: \nSelect and explain. \nA. B. subtilis, B. B. pumilis, C. Cl. tetani, D. B. stearothermophilus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Biological Sterilization Indicator of plasma sterilization: B. stearothermophillus, B. subtilis subspecies niger', 'role': 'assistant'}]