This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Pathology
[{'content': 'Null cells constitute what percentage of peripheral lymphocytes? \nSelect and explain. \nA. 0-1, B. 5-Feb, C. 10-May, D. 15-20', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) 5-10(Ref: Robbins 9th/pg 192; 8th/pg 188)Natural Killer Cells or Null cells constitute 5% to 10% of peripheral lymphocytes QAs NK cells neither have B nor T-cell markers, hence also called Null CellsNK cells destroy irreversibly stressed, virus-infected cells & tumor cells without prior exposure', 'role': 'assistant'}]