**Core Concept**
Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD) characterized by chronic inflammation and ulceration of the colonic mucosa, primarily affecting the rectum and extending proximally in a continuous manner. The pathogenesis of UC involves an interplay between genetic predisposition, environmental factors, and an abnormal immune response.

**Why the Correct Answer is Right**
The correct answer is related to the distinction between ulcerative colitis and other forms of IBD, such as Crohn's disease. Ulcerative colitis is typically characterized by the absence of granulomas, skip lesions, and transmural inflammation, which are more commonly seen in Crohn's disease. The mucosal injury in UC is confined to the epithelial layer, whereas in Crohn's disease, the inflammation extends to the deeper layers of the bowel wall.

**Why Each Wrong Option is Incorrect**
* **Option A:** Not a characteristic feature of ulcerative colitis.
* **Option B:** A common feature of ulcerative colitis, particularly in the acute phase.
* **Option C:** While not exclusive to ulcerative colitis, it can be seen in some cases, especially in the presence of dysplasia or malignancy.

**Clinical Pearl / High-Yield Fact**
A key radiological feature of ulcerative colitis is the "lead pipe" appearance of the colon on barium enema, which is due to the loss of haustral folds and the presence of a uniform, featureless mucosa.

**Correct Answer:** C.