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
All clostridia cause myonecrosis except? 
Select and explain. 
A. C septicum, B. C difficle, C. C novyi, D. C welchii
B: C difficle
Answer: B: C difficle 
Explanation: Ans. is 'b' i.e., C difficle