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
NK cells are components of 
Select and explain. 
A. Innate immunity, B. Acquired immunity, C. Adaptive immunity, D. None of the above
A: Innate immunity
Answer: A: Innate immunity 
Explanation: NK cells – Innate immunity.
B cells and T cells – Acquired immunity.