<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 47-year-old woman is brought to the emergency department by her husband with the complaints of severe abdominal pain and discomfort. The pain began 2 days earlier, she describes it as radiating to her back and is associated with nausea. Her past medical history is significant for similar episodes of pain after fatty meals that resolved on its own. She drinks socially and has a 15 pack-year smoking history. Her pulse is 121min, blood pressure is 12171 mm Hg, and her temperature is 103.1F 39.5C. She has tenderness in the right upper quadrant and epigastrium with guarding and rebound tenderness. Bowel sounds are hypoactive. Part of a CBC is given below. What is the next best step in the management of this patient?Hb: 11 gmdLTotal count WBC: 13,400mm3Differential count:Neutrophils: 80Lymphocytes: 15Monocytes: 5ESR: 45 mmhrC-reactive protein: 9.9 mgdL Normal 3.0 mgdL? A: Ultrasound of the appendix, B: Erect abdominal X-ray, C: Ultrasound of the gallbladder, D: Upper GI endoscopy, E: Serum lipase levels,  <response>: This is a patient presenting with right upper quadrant abdominal pain, fever, nausea and vomiting. Key findings on exam include right upper quadrant and epigastric tenderness, guarding and rebound tenderness. Lab tests show elevated inflammatory markers like WBC count, neutrophil percentage and CRP. The most likely diagnosis is acute cholecystitis inflammation of the gallbladder. Imaging of the gallbladder with ultrasound would be the next best step to confirm the diagnosis and assess for complications like gallstones, empyema, perforation etc. Choices A and B are not useful in evaluating suspected cholecystitis. Choice D, upper GI endoscopy, may be helpful later if evaluating for peptic ulcer disease but is not the immediate next step. Choice E, serum lipase, would be indicated if pancreatitis was suspected, but the location and nature of pain make cholecystitis more likely.C: Ultrasound of the gallbladder 