Which of the following is the most likely diagnosis? A 72-year old man is brought to the emergency department because of a 1-week history of increasingly severe abdominal pain, diarrhea, and loss of appetite. He had had a fever for 2 days. His temperature is 38.3C (101F), and pulse is 106/min. Abdominal examination shows distention and rebound tenderness localized to the left lower quadrant. His leukocyte count is 18,000/mm3 (80% segmented neutrophils, 10% bands, and 10% lymphocytes). An abdominal CT scan shows a 7-mm, thickened colonic wall, and pericolic fat inflammation; there is a collection of contrast in this region.
A. Amebiasis B. Collagenous colitis C. Colon cancer D. Diverticulitis E. Ulcerative colitis