**Core Concept**
Epithelial metaplasia in the context of chronic reflux is a type of adaptive response where the normal squamous epithelium lining the esophagus is replaced by a different type of epithelium, often as a result of chronic irritation and inflammation. This condition is a hallmark of Barrett's esophagus, a precursor to esophageal adenocarcinoma.

**Why the Correct Answer is Right**
The replacement of squamous epithelium with metaplastic epithelium is a result of chronic gastroesophageal reflux disease (GERD) causing damage to the esophageal lining. This damage triggers a reparative response, leading to the proliferation of columnar epithelial cells, often with goblet cells, which are characteristic of intestinal metaplasia. The intestinal metaplastic cells in Barrett's esophagus express markers such as CDX2 and MUC2, indicating their intestinal differentiation.

**Why Each Wrong Option is Incorrect**
**Option A:** Squamous epithelial cells are the normal lining of the esophagus, not metaplastic cells.
**Option B:** Mucous gland cells may be present in the esophagus but are not the primary cell type in metaplastic epithelium.
**Option C:** Paneth cells are found in the small intestine and are not typically associated with Barrett's esophagus.

**Clinical Pearl / High-Yield Fact**
Barrett's esophagus is a known precursor to esophageal adenocarcinoma, and patients with chronic GERD symptoms should be screened for this condition, especially if they have a family history of esophageal cancer or dysplasia.

**Correct Answer:** C. Goblet cells.