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
In considering the serological test for detection of HIV infection an early positive ELISA is due to: 
Select and explain. 
A. P24 antibody, B. Gp 120 antibody, C. Gp 120 antigen, D. P24 antigen
D: P24 antigen
Answer: D: P24 antigen 
Explanation: Ans: d