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
Which of following clostridia is non-invasive: 
Select and explain. 
A. Clostridium novyi, B. Clostridium botulinum, C. Clostridium perfringens, D. Clostridium tetani
B: Clostridium botulinum
Answer: B: Clostridium botulinum 
Explanation: Ans. is. 'b' i. e. Clostridium botulinum