## **Core Concept**
The question tests the ability to diagnose acute abdominal conditions in a patient with prolonged fever and new onset of abdominal pain. The key concepts here involve understanding the differential diagnoses for acute abdomen, particularly in a febrile patient, and correlating symptoms with possible causes.

## **Why the Correct Answer is Right**
The correct answer, **C. Typhoid intestinal perforation**, is likely because the patient has had a prolonged fever for 15 days, which is suggestive of typhoid fever caused by *Salmonella Typhi*. A known complication of untreated or late-treated typhoid fever is intestinal perforation, which presents acutely with severe abdominal pain, tenderness, guarding, and distension. The prolonged fever followed by acute abdominal symptoms points towards this diagnosis.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is not provided, but typically, other causes of acute abdomen such as appendicitis, perforated peptic ulcer, or ischemic bowel could be considered. However, the prolonged fever before the onset of abdominal symptoms makes these less likely.
- **Option B:** This option is not provided, but conditions like peritonitis or abdominal abscess could present with similar symptoms. However, they usually have a more acute onset and might not be preceded by such a prolonged fever unless secondary to another process.
- **Option D:** This option is not provided, but other infections or conditions leading to acute abdomen, such as a ruptured ectopic pregnancy (less likely in a male), could be considered. The history of prolonged fever, however, steers the diagnosis away from these.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that typhoid fever can have a varied presentation, and a complication like intestinal perforation significantly increases mortality. Early recognition and treatment are critical. In areas endemic for typhoid, a high index of suspicion is necessary for early diagnosis and prevention of complications.

## **Correct Answer: C. Typhoid intestinal perforation.**