This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Microbiology
Classical complement activated by: 
Select and explain. 
A. C1, B. C3 Convease, C. lgA, D. Ag - Ab complex
D: Ag - Ab complex
Answer: D: Ag - Ab complex 
Explanation: Antigen-antibody complex lead to activation of classical complement pathway. MAC - Membrane attack complex (C5 - C9) MAC-attack on Antigen & make pores and finally antigen killed Alternate Complement pathway - staing from C3QQ Note : - Compliment 1,4,2 is by passed Lectin pathway sta from C4 C1 will not be consumed in lectin pathway