A 45-year-old man with HIV infection and a CD4+ count of 180 cells/μL presents to the emergency department with a 4-day history of progressive dyspnea, nonproductive cough, and fever. Vital signs show temperature 38.5°C, respiratory rate 24 breaths/min, and oxygen saturation 89% on room air. Chest X-ray demonstrates bilateral interstitial infiltrates. Serum LDH is 485 U/L. Pneumocystis jirovecii pneumonia (PCP) is diagnosed and treatment is initiated with trimethoprim-sulfamethoxazole (TMP-SMX) and prednisone. On hospital day 3, the patient develops a fever of 39.2°C, a diffuse maculopapular rash involving the trunk and extremities, and laboratory studies reveal a peripheral eosinophil count of 11%. The rash is non-bullous and does not involve mucous membranes. Which of the following best explains these clinical findings?

1. A)Sulfonamide hypersensitivity reaction occurring at higher frequency in HIV-infected patientsGABARITO
2. B)Immune reconstitution inflammatory syndrome (IRIS) triggered by rapid CD4+ recovery from antiretroviral therapy
3. C)Drug fever from trimethoprim-induced interference with folate metabolism
4. D)Acute hemolytic anemia secondary to TMP-SMX-induced oxidative stress in glucose-6-phosphate dehydrogenase deficiency
5. E)Microbiologic treatment failure with persistent Pneumocystis infection and progressive pulmonary inflammation