**Core Concept**
Typhoid ulcers are a hallmark of typhoid fever, a systemic infection caused by *Salmonella Typhi*. These ulcers occur in the ileum, the last part of the small intestine, due to the invasion of the bacteria and subsequent inflammation and necrosis of the intestinal mucosa.

**Why the Correct Answer is Right**
Typhoid ulcers are typically solitary, and their presence is often associated with systemic manifestations such as fever, abdominal pain, and rash. The ulcers are usually located in the ileum, and their presence can be confirmed by endoscopy or biopsy. The pathogenesis of typhoid ulcers involves the invasion of *Salmonella Typhi* into the intestinal mucosa, leading to inflammation and necrosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because typhoid ulcers are typically solitary and not multiple. The presence of multiple ulcers would be more suggestive of other conditions such as Crohn's disease or ulcerative colitis.

**Option B:** This option is incorrect because typhoid ulcers are not typically located in the jejunum. While the jejunum can be involved in typhoid fever, the ulcers are more commonly found in the ileum.

**Option C:** This option is incorrect because typhoid ulcers are not typically associated with gastrointestinal bleeding. While gastrointestinal bleeding can occur in typhoid fever, it is not a characteristic feature of the ulcers themselves.

**Option D:** This option is incorrect because typhoid ulcers are not typically associated with a mass. While a mass can occur in the case of a typhoid ulcer, it is not a characteristic feature of the condition.

**Clinical Pearl / High-Yield Fact**
Typhoid ulcers are a classic example of a "silent" lesion, meaning that they can be present without causing significant symptoms. This highlights the importance of maintaining a high index of suspicion for typhoid fever in patients with systemic symptoms and a history of exposure to contaminated food or water.

**Correct Answer: A.**