This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (E.N.T.), Subject name: ENT
[{'content': 'Human immunodeficiency virus (HIV) affects the immune response. The primary change brought about is: \nSelect and explain. \nA. A gammaglobulinemia, B. Defect in cell-mediated immunity, C. Defect in complement system, D. Defect in natural killer cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: HIV infects CD4 (helper) T-lymphocytes, macrophages and monocytes and leads to cell-mediated immune deficiency which predisposes to opportunistic infections and malignancies.', 'role': 'assistant'}]