<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 6-year-old boy is brought to the emergency department because of colicky abdominal pain and vomiting for 1 day. He has a history of a sore throat 2 weeks ago. His temperature is 37C 98.6F, pulse is 100min, blood pressure is 9055, and respirations are 28min. Examination of the lower extremities shows non-blanching raised erythematous papules. The abdomen is soft and nontender. Bowel sounds are high-pitched. Both ankles are swollen and tender; range of motion is limited by pain. Test of the stool for occult blood is positive. Laboratory studies show:Hemoglobin 13.1 gdLLeukocyte count 9800mm3Platelet count 265,000mm3SerumGlucose 78 mgdLAntinuclear antibodies negativeUrineGlucose negativeProtein negativeBlood 2RBC 10-12hpf with dysmorphic featuresWBC 0-1hpfUltrasonography of the abdomen shows a portion of the bowel with alternating echogenic and hypoechogenic bands in transverse view. Which of the following is the most likely cause of these findings?? A: P-ANCA vasculitis of small vessels, B: Microthrombi occluding the vasculature, C: Gram-negative cocci infection, D: Deposition of IgA immune complexes, E: HLA-associated synovial inflammation,  <response>: This is a clinical case scenario involving a 6-year-old boy with abdominal pain, vomiting, fever, rash, joint swelling, and laboratory findings suggestive of anemia, inflammation, and possible gastrointestinal bleeding. The key findings are the rash, arthritis, abdominal pain, hematuria with dysmorphic RBCs, and ultrasound findings. The differential diagnosis includes:- Henoch-Schonlein purpura HSP: This vasculitic disorder often presents with the triad of rash, arthritis, and abdominal pain. It can cause glomerulonephritis with hematuria. The ultrasound findings are consistent with bowel wall edema seen in HSP.- Infection: The history of sore throat raises suspicion for post-infectious process like reactive arthritis or IgA nephropathy. However, the rash and ultrasound findings make this less likely.- Other vasculitides like polyarteritis nodosa are less likely given the clinical presentation. The ultrasound findings, palpable purpuric rash, arthritis, and renal involvement point toward HSP as the most likely diagnosis.D: Deposition of IgA immune complexes 