You are answering a USMLE-style medical question. Question: A 48-year-old woman comes to the emergency department because of a 1-day history of fever, vomiting, and abdominal pain. Two weeks ago, while visiting Guatemala, she had an emergency appendectomy under general inhalational anesthesia. During the surgery, she received a transfusion of 1 unit of packed red blood cells. Her temperature is 38.3°C (100.9°F) and blood pressure is 138/76 mm Hg. Examination shows jaundice and tender hepatomegaly. Serum studies show: Alkaline phosphatase 102 U/L Aspartate aminotransferase 760 U/L Bilirubin Total 3.8 mg/dL Direct 3.1 mg/dL Anti-HAV IgG positive Anti-HAV IgM negative Anti-HBs positive HBsAg negative Anti-HCV antibodies negative Abdominal ultrasonography shows an enlarged liver. A biopsy of the liver shows massive centrilobular necrosis. Which of the following is the most likely underlying cause of this patient's condition?" Options: A) Acalculous inflammation of the gallbladder B) Virus-mediated hepatocellular injury C) Adverse effect of anesthetic D) Gram-negative bacteria in the bloodstream Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.