**Core Concept**
Typhoid ulcer is a complication of typhoid fever, characterized by bleeding ulcers in the small intestine, particularly in the ileum. The pathogenesis involves the invasion of Salmonella Typhi bacteria into the intestinal mucosa, leading to inflammation, necrosis, and ulceration.

**Why the Correct Answer is Right**
Typhoid ulcers are typically located in the ileum, which is the last part of the small intestine. The ulcers are usually multiple and can bleed, leading to gastrointestinal bleeding. The pathogenesis of typhoid ulcers involves the invasion of Salmonella Typhi bacteria into the intestinal mucosa, leading to inflammation and necrosis. The bacteria can also cause a severe inflammatory response, leading to the formation of ulcers.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be incorrect because it is not a characteristic of typhoid ulcers. Typhoid ulcers are typically found in the ileum, not in the stomach or duodenum.

**Option B:** This option might be incorrect because it is not a typical location for typhoid ulcers. While typhoid ulcers can occur in the jejunum, they are more commonly found in the ileum.

**Option C:** This option might be incorrect because it is not a characteristic of typhoid ulcers. Typhoid ulcers are typically multiple and can bleed, but they are not typically solitary.

**Option D:** This option might be incorrect because it is not a characteristic of typhoid ulcers. While typhoid ulcers can cause gastrointestinal bleeding, they are not typically associated with perforation.

**Clinical Pearl / High-Yield Fact**
Typhoid ulcers are a classic complication of typhoid fever and can be a cause of gastrointestinal bleeding. Remember that typhoid ulcers are typically multiple and occur in the ileum.

**Correct Answer: C. Solitary ulcers are not characteristic of typhoid ulcers.**