This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
[{'content': 'In considering the serological test for detection of HIV infection an early positive ELISA is due to: \nSelect and explain. \nA. P24 antibody, B. Gp 120 antibody, C. Gp 120 antigen, D. P24 antigen', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans: d', 'role': 'assistant'}]