This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
All are true regarding NK cells except - 
Select and explain. 
A. CD 16 & CD 56 positive, B. Secrete complement like substance, C. Impoant role in viral infected cell, D. None
D: None
Answer: D: None 
Explanation: NK cells have both CD16 and CD56 on their surface. Like the membrane attack complex produced by complement pathway, they produce perforins that forms pores through which granzymes enter the cell. They are considered as an innate immune defence against cells that have lost the expression of ClassI MHC like virus infected cells and malignant cells. Reff: Ananthanarayanan & Panikers textbook of microbiology 9th edition pg: 137