**Core Concept**
Cobblestoning of the intestine refers to a characteristic appearance of the intestinal mucosa, which is rough and irregular due to thickening of the intestinal folds and the presence of lymphoid aggregates. This finding is often associated with certain gastrointestinal disorders, particularly those involving abnormal immune responses or chronic inflammation.

**Why the Correct Answer is Right**
The "string sign" is a radiological term used to describe a narrow, thread-like appearance of a bowel segment on imaging studies. In the context of cobblestoning, the string sign is often seen in Crohn's disease, a type of inflammatory bowel disease (IBD) characterized by chronic inflammation of the gastrointestinal tract. The inflammation leads to thickening of the intestinal wall, narrowing of the lumen, and the characteristic cobblestoning appearance on imaging. The string sign is thought to be caused by fibrosis and scarring of the intestinal wall, which leads to narrowing of the bowel lumen.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the characteristic radiological findings associated with cobblestoning and the string sign.
* **Option B:** This option is incorrect because it is a different gastrointestinal disorder that does not typically present with cobblestoning or the string sign.
* **Option D:** This option is incorrect because it is a different condition that affects the small intestine, but it does not typically present with the characteristic radiological findings of cobblestoning and the string sign.

**Clinical Pearl / High-Yield Fact**
Cobblestoning and the string sign are classic radiological findings in Crohn's disease, but they can also be seen in other conditions such as Whipple's disease or graft-versus-host disease. It's essential to consider the clinical context and other supporting evidence when interpreting these findings.

**Correct Answer:** C. Crohn's disease