A 32-year-old female with no significant past medical history except for a recent upper respiratory infection treated with antibiotics, presents with symptoms of fatigue, frequent infections, and unexplained bruising. Over the last few months, she noticed increased shortness of breath upon minimal exertion and an unusual tendency to bruise easily after minor bumps. Her symptoms escalated to include prolonged bleeding from minor cuts, leading her to seek medical attention. Initial blood work revealed severe pancytopenia with a hemoglobin of 7.5 g/dL, white blood cell count of 1.2 x 10^9/L, and platelets at 20 x 10^9/L. A bone marrow biopsy was conducted due to the suspicion of bone marrow failure. The biopsy confirmed the diagnosis of aplastic anemia, showing a hypocellular marrow with increased fat spaces and decreased hematopoietic cells. Which of the following can cause aplastic anemia?
