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
[{'content': 'Virus infected cells are killed by - \nSelect and explain. \nA. Macrophages, B. Complement system, C. MHC II related cells, D. NK cells', 'role': 'user'}, {'content': 'Answer: D \nExplanation: NK cells 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', 'role': 'assistant'}]