<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 65-year-old male presents to the emergency department with a 2-day onset of right-lower quadrant and right flank pain. He also states that over this period of time he has felt dizzy, light-headed, and short of breath. He denies any recent trauma or potential inciting event. His vital signs are as follows: T 37.1 C, HR 118, BP 7446, RR 18, SpO2 96. Physical examination is significant for an irregularly irregular heart rhythm as well as bruising over the right flank. The patients medical history is significant for atrial fibrillation, hypertension, and hyperlipidemia. His medication list includes atorvastatin, losartan, and coumadin. IV fluids are administered in the emergency department, resulting in an increase in blood pressure to 10060 and decrease in heart rate to 98. Which of the following would be most useful to confirm this patients diagnosis and guide future management?? A: Ultrasound of the right flank, B: Radiographs of the abdomen and pelvis, C: Magnetic resonance angiography, D: MRI abdomenpelvis, E: CT abdomenpelvis,  <response>: This is a clinical vignette describing a 65-year-old male with sudden onset right lower quadrant and flank pain, dizziness, lightheadedness, shortness of breath, and hypotension. Key findings include irregularly irregular heart rhythm, bruising over the right flank, history of atrial fibrillation on anticoagulation with coumadin, and improvement in vitals with IV fluids. The differential diagnosis includes retroperitoneal hemorrhage, such as from a ruptured abdominal aortic aneurysm. Imaging is needed to confirm the diagnosis and guide management. Ultrasound could identify free fluid but would not fully characterize the source. Radiographs are insensitive for retroperitoneal processes. MRA could identify aortic pathology but CT is more sensitive and specific for diagnosing retroperitoneal hemorrhage. MRI may demonstrate hemorrhage but CT is faster and more appropriate in an unstable patient.E: CT abdomenpelvis 