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: Pathology
HLA-I is present on ? 
Select and explain. 
A. All nucleated cells, B. Only on cells of immune system, C. Only on B-cells, D. Only on T-cells
A: All nucleated cells
Answer: A: All nucleated cells 
Explanation: Ans. is 'a' i.e., All nucleated cells