This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Microbiology
[{'content': 'Efficacy of Moist Heat Sterilization is tested by using the Spores of \nSelect and explain. \nA. Bacillus stearothermophilus, B. Clostridium tetani, C. Bacillus subtilis, D. Clostridium botulinum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) Bacillus stearothermophilus > For determining the efficacy of moist heat sterilization, (e.g. autoclaving), spores of Bacillus stearothermophilus are used as the test organism. This a thermophilic organism with an optimum growth temp. 55-60degC. Its spores are killed at 121 degC after 12 min exposure.', 'role': 'assistant'}]