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
Biological indicator for determining efficacy of autoclaving is: September 2009 
Select and explain. 
A. Pseudomonas aeruginosa, B. Clostridium Perfringenes, C. Bacillus stearothermophilus, D. Salmonella typhi
C: Bacillus stearothermophilus
Answer: C: Bacillus stearothermophilus 
Explanation: Ans. C: Bacillus stearothermophilus