What biopsy evidence supports a diagnosis of ulcerative colitis?

The diagnosis of ulcerative colitis is supported by the presence of superficial mucosal inflammation, primarily involving the rectum and colon. This condition is characterized by inflammatory infiltrate limited to the mucosa and submucosa, which can include an increased number of plasma cells, suggesting an immune response in the colonic mucosa.

Option C highlights the key histological features seen in patients with ulcerative colitis—specifically, the superficial mucosal inflammation coupled with plasma cell infiltration. These findings align with the pattern of injury observed in ulcerative colitis, where the inflammation primarily affects the upper layers of the intestinal wall rather than penetrating deeper layers.

In contrast, other choices present histological characteristics not consistent with ulcerative colitis. For example, villus blunting with increased lymphocytes is more characteristic of conditions like celiac disease, where there is damage to the villi due to an autoimmune response. Transmural inflammation, seen in conditions like Crohn's disease, affects the entire thickness of the bowel wall and can lead to complications such as strictures and fistulae. Granuloma formation is a defining feature of Crohn's disease, not ulcerative colitis, which typically does not display granulomas.

Therefore, the biopsy