You are answering a USMLE-style medical question. Question: A 10-year-old girl is brought to the physician because of high-grade fever, myalgia, and generalized fatigue for 3 days. She returned from a vacation to northern Brazil 4 days ago. She took the appropriate medications and immunizations prior to her visit. There is no family history of serious illness. She appears ill. Her temperature is 39.4°C (103°F), pulse is 110/min and blood pressure is 94/54 mm Hg. Examination shows jaundice of the conjunctivae and skin. The abdomen is soft and nontender; the spleen is palpated 2 to 3 cm below the left costal margin. Laboratory studies show: Hemoglobin 10.1 g/dL Leukocyte count 4,650/mm3 Platelet count 200,000/mm3 Serum Glucose 56 mg/dL Creatinine 0.8 mg/dL Bilirubin Total 4.7 mg/dL Direct 0.9 mg/dL Lactate dehydrogenase 212 U/L Which of the following is the most likely to confirm the diagnosis?" Options: A) Thick and thin blood smear B) Direct antiglobulin test C) Sickle cell test D) Ultrasound of the abdomen Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.