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 compliment blinds with Fc poion of IgM in Classic pathway ? 
Select and explain. 
A. CI, B. C2, C. C3, D. C4
A: CI
Answer: A: CI 
Explanation: Ans. is 'a' i.e., C1 C1q poion of C1 binds to the Fc poion of IgM (CH2 region) and IgG (CH4 region).