<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .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 wifes arms. Upon admission, he is found to have a blood pressure of 7840 mm Hg, a pulse of 140min, 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,  <response>: This is a patient with acute gastrointestinal bleeding presenting with hypotension and tachycardia. The most urgent next step is to stabilize the patient, so diagnostic tests that do not directly impact immediate management should not be prioritized. Of the options given, nasogastric lavage can quickly assess if the bleeding is coming from an upper GI source and can help stabilize the patient by clearing blood from the stomach. Colonoscopy and upper endoscopy, while important for eventual diagnosis, do not help stabilize the patient. Mesenteric angiography and radionuclide imaging may help locate the bleeding source but do not have an immediate impact on stabilization. Therefore, the best next step is nasogastric lavage.B: Nasogastric lavage 