A 32-year-old woman who lives in Pensacola, Florida, goes to the physician because of increasingly severe dyspnea,orthopnea, and swelling of the legs for the past 2 weeks. She has no previous history of serious illness or surgery. On physical examination, her temperature is 37.8C, pulse is 83/min, respirations are 20/min, and blood pressure is 100/60 mm Hg. An ECG shows episodes of ventricular tachycardia. An echocardiogram shows right and left ventricular dilation, but no valvular deformities. An endomyocardial biopsy shows focal myocyte necrosis and lymphocytic infiltrate. Which of the following organisms most likely caused the infection? (A) Trypanosoma cruzi (B) Viridans streptococci (C) Coxsackievirus A (D) Toxoplasma gondii (E) Staphylococcus aureus (F) Mycobacterium kans asii