question: Q:A 56-year-old man comes to the emergency department because of progressively worsening shortness of breath and fever for 2 days. He also has a nonproductive cough. He does not have chest pain or headache. He has chronic myeloid leukemia and had a bone marrow transplant 3 months ago. His current medications include busulfan, mycophenolate mofetil, tacrolimus, and methylprednisolone. His temperature is 38.1°C (100.6°F), pulse is 103/min, respirations are 26/min, and blood pressure is 130/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 93%. Pulmonary examination shows diffuse crackles. The spleen tip is palpated 4 cm below the left costal margin. Laboratory studies show:
  Hemoglobin 10.3 g/dL
  Leukocyte count 4,400/mm3
  Platelet count 160,000/mm3
  Serum
  Glucose 78 mg/dL
  Creatinine 2.1 mg/dL
  D-dimer 96 ng/mL (N < 250)
  pp65 antigen positive
  Galactomannan antigen negative
  Urinalysis is normal. An x-ray of the chest shows diffuse bilateral interstitial infiltrates. An ECG shows sinus tachycardia. Which of the following is the most appropriate pharmacotherapy?"? 
  {'A': 'Levofloxacin', 'B': 'Valganciclovir', 'C': 'Acyclovir', 'D': 'Ganciclovir', 'E': 'Azithromycin'},