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
Not true regarding NK cells - 
Select and explain. 
A. Active against malignant cells, B. Inactive MHC antigen for killing microorganisms, C. First line defense against viral infections, D. No prior sensitization required
B: Inactive MHC antigen for killing microorganisms
Answer: B: Inactive MHC antigen for killing microorganisms 
Explanation: NK cell's cytotoxicity is not antibody dependent or MHC restricted :NK cellsNatural killer cells Reff: Anantharayan & Panikers textbook f microbiology 9th edition pg:137