<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 27-year-old woman with sickle cell disease and at 39-weeks gestation is brought to the emergency department in active labor. She has had multiple episodes of acute chest syndrome and has required several transfusions in the past. She has a prolonged vaginal delivery complicated by postpartum bleeding, and she receives a transfusion of 1 unit of packed red blood cells. One hour later, the patient experiences acute flank pain. Her temperature is 38.7C 101.6F, pulse is 115min, respirations are 24min, and blood pressure is 9555 mm Hg. Foley catheter shows dark brown urine. Further evaluation of this patient is most likely to show which of the following?? A: Bilateral pulmonary infiltrates on chest x-ray, B: Serum antibodies against class I HLA antigens, C: Positive direct Coombs test, D: Positive blood cultures, E: Low levels of serum IgA immunoglobulins,  <response>: This is a patient with sickle cell disease who developed acute flank pain, fever, tachycardia, tachypnea, and hypotension after receiving a blood transfusion. The description of dark brown urine suggests hemoglobinuria. The main concern here is a hemolytic transfusion reaction. These reactions occur when the recipient has preformed antibodies against donor red blood cell antigens, leading to hemolysis of the transfused cells. Choice A describes acute chest syndrome, which this patient has a history of but is unrelated to the transfusion reaction. Choice B describes the presence of HLA antibodies, which could cause a reaction but would not lead to hemolysis.Choice C describes a positive direct Coombs test, which detects antibodies bound to the patients own RBCs. This would not be expected in a transfusion reaction where the antibodies are against donor cells.Choice D may be seen with a bacterial infection but does not explain hemolysis.Choice E describes an immunodeficiency unrelated to the transfusion reaction.The correct answer is therefore choice C, as a positive direct Coombs test would detect anti-donor antibodies bound to the transfused RBCs, indicating an immune-mediated hemolytic transfusion reaction.C: Positive direct Coombs test 