This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'N.K. Cell provides immunity against \nSelect and explain. \nA. Virus, B. Bacteria, C. Fungus, D. Chlamydia', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Virus . NK cells are considered to be impoant in immune surveillance and natural defence against virus infected cells and malignant mutant cells.", 'role': 'assistant'}]