This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'HIV affects CD4 cells by which protein \nSelect and explain. \nA. Gp 120, B. GP 41, C. CCR5, D. CXCR4', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ref Robbins 8/e p246-247 HIV 1 uses CD 4 to gain entry into T cells and achieve this through it's viral envelope protein known as gp120", 'role': 'assistant'}]