**Core Concept**
Gallstone ileus is a rare complication of gallstone disease, where a gallstone enters the intestinal tract through a fistula, typically between the gallbladder and the small intestine. This can lead to intestinal obstruction, which may require surgical intervention.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of gallstone ileus. A gallstone ileus typically occurs when a gallstone, usually a large one, enters the intestinal tract through a fistula, often between the gallbladder and the duodenum (first part of the small intestine). The stone then travels through the intestinal tract until it becomes lodged in a narrower section of the intestine, causing an obstruction.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because gallstone ileus is not typically caused by a cancerous growth in the intestine. While tumors can cause intestinal obstruction, this is not a characteristic feature of gallstone ileus.
* **Option B:** This option is incorrect because the presentation of gallstone ileus is usually acute, with severe abdominal pain and vomiting, rather than a chronic, gradual onset of symptoms.
* **Option C:** This option is incorrect because the treatment of gallstone ileus typically involves surgical intervention, such as enterotomy or ileostomy, rather than conservative management with antibiotics or bowel rest.

**Clinical Pearl / High-Yield Fact**
Gallstone ileus can be a life-threatening condition if not promptly diagnosed and treated. A high index of suspicion is required, particularly in patients with a history of gallstones and symptoms of intestinal obstruction.

**Correct Answer:** D