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
Plasma sterilization acuracy is assessed by using ? 
Select and explain. 
A. Bacillus subtilis, B. Bacillus stereothermophilus, C. Staphylococcus aureus, D. Clostidium tetani
B: Bacillus stereothermophilus
Answer: B: Bacillus stereothermophilus 
Explanation: Ans. is 'b' i.e., Bacillus stereothermophilus