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
Cytolytic activity of membrane attack complex is modulated by ? 
Select and explain. 
A. Factor I, B. Factor B, C. Factor S, D. Factor H
C: Factor S
Answer: C: Factor S 
Explanation: Ans. is 'c' i.e., Factor S