A 24-year-old man presents to the physician with an 8-week history of fevers, weight loss, sore throat, diarrhea, and arthralgias. Past medical history is unremarkable. He does not drink alcohol or smoke cigarettes and has not had any recent travel. Physical examination reveals anterior cervical and axillary lymphadenopathy as well as pharyngeal edema and hyperemia. Laboratory tests are ordered, and primary screening has ruled in a diagnosis of human immunodeficiency virus (HIV) infection.

Which of the following biological materials is used for the standard confirmatory measure for HIV infection?

• A) CC-type chemokine receptor 5 (CCR5) variant
• B) Deoxyribonucleic acid (DNA)
• C) H1 linker histone
• D) Protein
• E) (Ribonucleic acid) RNA