A 32-year-old woman with a 3-month history of progressive exertional dyspnea and nonproductive cough presents to the emergency department. She reports unintentional weight loss and night sweats for 2 months. She denies prior HIV testing or antiretroviral therapy. Vital signs show tachypnea (respiratory rate 28/min) and oxygen saturation of 88% on room air. Chest X-ray reveals bilateral interstitial infiltrates with a ground-glass appearance. Bronchoalveolar lavage demonstrates foamy macrophages and Pneumocystis jirovecii organisms. Laboratory values show CD4+ T cell count of 48 cells/μL (normal 500-1500), HIV viral load of 450,000 copies/mL, and normal absolute neutrophil and B cell counts. She is started on TMP-SMX, prednisone, and antiretroviral therapy. Which of the following mechanisms best explains this patient's inability to mount an adequate immune response to Pneumocystis jirovecii?

1. A)Direct infection of macrophages by HIV prevents effective antigen presentation to T cells
2. B)Progressive loss of CD4+ T helper cells through HIV-mediated cell lysis and apoptosis impairs coordinated immune responsesGABARITO
3. C)Preferential infection of CD8+ cytotoxic T cells by HIV results in loss of cytotoxic function against infected cells
4. D)HIV-induced thymic involution prevents generation of new naive T cells to replace infected cells
5. E)Decreased production of granulocyte-macrophage colony-stimulating factor due to loss of Th1 CD4+ T cell function impairs fungal clearance