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
Virus infected cells killed by: 
Select and explain. 
A. Natural killer cells, B. Plasma cells, C. B cells, D. None
A: Natural killer cells
Answer: A: Natural killer cells 
Explanation: Ans. is 'a'(Ref: Ananthanarayan, 8th/e, p. 131)Virus infected cells are killed by:(i) Innate immunity-by NK cells.(ii) Adaptive immunity-by cytotoxic T cells.