This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
The HIV virus binds directly to the surface receptors of CD4 lymphocytes with _____. 
Select and explain. 
A. Reverse transcriptase, B. Integrase, C. Hemagglutinin, D. Glycoprotein 120
D: Glycoprotein 120
Answer: D: Glycoprotein 120 
Explanation: HIV’s envelope contains two glycoproteins, gp120 and gp41. gp120 binds specifically with CD4 surface receptors.