**Core Concept**
Ulceration of Peyer's patches is a characteristic feature of certain gastrointestinal infections, which involves the pathological changes in the lymphoid tissues of the small intestine. Peyer's patches are small, flat, and oval-shaped lymphoid follicles located in the ileum, playing a crucial role in immune surveillance.

**Why the Correct Answer is Right**
The correct answer is associated with Yersinia enterocolitica infection. Yersinia enterocolitica is a gram-negative bacterium that invades the intestinal mucosa, leading to the formation of microabscesses and subsequent ulceration of Peyer's patches. This occurs due to the expression of the outer membrane protein YopB, which facilitates the invasion of epithelial cells and the disruption of the intestinal barrier. The ulceration of Peyer's patches is a hallmark of Yersinia enterocolitica infection and can lead to symptoms such as abdominal pain, diarrhea, and fever.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Shigella infection primarily causes ulceration of the colonic mucosa, rather than Peyer's patches.

**Option B:** This option is incorrect because Salmonella Typhi infection primarily causes systemic illness, such as fever and malaise, rather than localized gastrointestinal symptoms.

**Option C:** This option is incorrect because Campylobacter jejuni infection primarily causes enteritis, characterized by diarrhea, abdominal pain, and fever, rather than the specific ulceration of Peyer's patches.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the ulceration of Peyer's patches is a characteristic feature of Yersinia enterocolitica infection, and this should be considered in the differential diagnosis of patients presenting with gastrointestinal symptoms.

**Correct Answer: D. Yersinia enterocolitica**