You are answering a USMLE-style medical question. Question: A 3-year-old boy is brought to the physician because of a 3-day history of fatigue and yellow discoloration of his skin. One week ago, he had an upper respiratory tract infection. Examination shows jaundice of the skin and conjunctivae. The spleen tip is palpated 2 cm below the left costal margin. His hemoglobin concentration is 9.4 g/dl and his mean corpuscular hemoglobin concentration is 39% Hb/cell. A Coombs test is negative. A peripheral blood smear is shown. This patient is at greatest risk for which of the following complications? Options: A) Acute myelogenous leukemia B) Cholecystitis C) Renal papillary necrosis D) Splenic sequestration crisis Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.