A 42-year-old man complains of severe general weakness, significant weight loss, and frequent fungal infections of the oral cavity. He has history of recurrent herpes. Immunological testing reveals critically low levels of CD4+ T-lymphocytes (180 cells/mcL) in his peripheral blood. What disease can be characterized by such changes?

• A. Primary immunodeficiency
• B. Disseminated candidiasis
• C. Infectious mononucleosis
• D. HIV/AIDS
• E. Generalized tuberculosis