question: Q:A 74-year-old man is brought to the emergency department after he had copious amounts of blood-stained stools. Minutes later, he turned sweaty, felt light-headed, and collapsed into his wife’s arms. Upon admission, he is found to have a blood pressure of 78/40 mm Hg, a pulse of 140/min, and oxygen saturation of 98%. His family history is relevant for both gastric and colorectal cancer. His personal history is relevant for hypertension, for which he takes amlodipine. After an initial successful resuscitation with intravenous fluids, which of the following should be the first step in approaching this case?? 
  {'A': 'Colonoscopy', 'B': 'Nasogastric lavage', 'C': 'Upper endoscopy', 'D': 'Mesenteric angiography', 'E': 'Radionuclide imaging'},