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
The most frequently encountered clostridia' species in gas gangrene is 
Select and explain. 
A. Clostridium botulinum, B. Clostridium welchii, C. Clostridium tetani, D. Clostridium difficile
B: Clostridium welchii
Answer: B: Clostridium welchii 
Explanation: None