<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 69-year-old man is brought to the emergency department because of severe abdominal pain radiating to his left flank for 30 minutes. He is weak and has been unable to stand since the onset of the pain. He vomited twice on the way to the hospital. He has not passed stools for 3 days. He has hypertension, coronary heart disease, and peptic ulcer disease. He has smoked half a pack of cigarettes daily for 46 years. Current medications include enalapril, metoprolol, aspirin, simvastatin, and pantoprazole. He appears ill. His temperature is 37C 98.6F, pulse is 131min, respirations are 31min, and blood pressure is 8256 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 92. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. Examination shows a painful pulsatile abdominal mass. Intravenous fluid resuscitation is begun. Which of the following is the most appropriate next step in management?? A: Supine and erect x-rays of the abdomen, B: CT scan of the abdomen and pelvis with contrast, C: Open emergency surgery, D: Transfusion of packed red blood cells, E: Colonoscopy,  <response>: This is a question about a 69-year-old man with severe abdominal pain radiating to his left flank, vomiting, constipation, and a pulsatile abdominal mass on exam. He is hypotensive with tachycardia. The key findings are the acute onset of severe abdominal pain with hypotension and a pulsatile abdominal mass, which indicate a likely abdominal aortic aneurysm that has ruptured. The most appropriate next step is immediate surgery, as a ruptured AAA is a surgical emergency requiring prompt repair to prevent exsanguination. Choice C for open emergency surgery is therefore the best answer. Choice A for X-rays would delay needed surgery. Choice B for CT scan may help further delineate the anatomy but would delay surgery. Choices D and E are not appropriate next steps.C: Open emergency surgery 