A 30-year-old man presents with 4 months of bloody diarrhea, tenesmus, and lower abdominal cramping. Vital signs show BP 128/82 mmHg, HR 92/min, RR 16/min, temperature 37.2°C, and SpO2 98% on room air. Colonoscopy reveals continuous inflammation beginning in the rectum extending through the sigmoid colon with loss of haustra. Biopsy demonstrates mucosal and submucosal inflammation with crypt abscesses. Laboratory studies show hemoglobin 12.5 g/dL. He denies extraintestinal manifestations. Which of the following is the most likely diagnosis?

1. A)Crohn disease
2. B)Ulcerative colitisGABARITO
3. C)Diverticulosis
4. D)Ischemic colitis
5. E)Microscopic colitis