**Core Concept**
The folds of Hoboken, also known as the plicae circulares, are a series of circular folds in the small intestine that increase the surface area for absorption of nutrients. These folds are a key anatomical feature of the intestinal mucosa, playing a crucial role in the digestion and absorption of nutrients.

**Why the Correct Answer is Right**
The folds of Hoboken are formed by the contraction of smooth muscle cells in the muscularis mucosae, which causes the mucosa to fold inward. This increases the surface area of the mucosa, allowing for greater absorption of nutrients from the lumen. The presence of these folds is essential for efficient nutrient absorption in the small intestine.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the plicae circulares are not found in the large intestine, which primarily functions for water absorption and storage of feces.
**Option B:** Incorrect because the plicae circulares are not associated with the stomach, which is primarily responsible for mechanical and chemical digestion of food.
**Option C:** Incorrect because the plicae circulares are not found in the duodenum, although the duodenum is the first part of the small intestine and plays a key role in nutrient absorption.

**Clinical Pearl / High-Yield Fact**
Remember that the folds of Hoboken are a characteristic feature of the small intestine and play a crucial role in nutrient absorption. This is a key concept to recall when studying gastrointestinal anatomy and physiology.

**Correct Answer: C. Small intestine.