A 28-year-old woman with a 5-year history of ulcerative colitis presents to the emergency department with acute onset severe abdominal pain, bloody diarrhea (8-10 stools daily), and fever to 38.9°C. Her current medications include mesalamine and an inhaled corticosteroid for mild asthma. Vital signs: BP 105/68 mmHg, HR 112/min, RR 22/min, SpO2 98% on room air. On examination, the abdomen is markedly distended with diminished bowel sounds. Laboratory studies show WBC 14.2 K/μL, Hgb 9.8 g/dL, albumin 2.8 g/dL, and creatinine 1.4 mg/dL (baseline 0.9). Abdominal radiography demonstrates colonic dilation to 8 cm without perforation. Which of the following is the most appropriate immediate management?

1. A)Initiate high-dose IV corticosteroids, bowel rest, IV hydration, and broad-spectrum antibioticsGABARITO
2. B)Perform urgent colonoscopy with biopsy to assess mucosal healing and guide escalation therapy
3. C)Start anti-TNF therapy (infliximab) as expedited rescue therapy to avoid surgical intervention
4. D)Administer high-dose antispasmodic agents and continue oral mesalamine to maintain mucosal coverage
5. E)Proceed directly to surgical consultation for total proctocolectomy given toxic megacolon