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 component of the cell wall is responsible for endotoxic activity: 
Select and explain. 
A. Region I, B. Region II, C. Region III, D. Biovin antigen
C: Region III
Answer: C: Region III 
Explanation: None