**Core Concept**
In a normal gallbladder, the epithelial lining is a crucial structure that plays a key role in bile production and storage. The gallbladder epithelium is composed of a specific type of cell that is responsible for the secretion and absorption of bile salts.

**Why the Correct Answer is Right**
In a normal gallbladder, the epithelial lining is typically composed of a single layer of columnar epithelial cells, also known as mucous cells. These cells are responsible for the secretion of mucin, which helps to protect the gallbladder and bile ducts from bile salts. The correct answer reflects this normal histological finding.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it implies the presence of a different type of epithelial lining, such as squamous or cuboidal epithelium, which is not characteristic of a normal gallbladder.

**Option B:** This option is incorrect because it suggests the presence of a pathological process, such as chronic inflammation or cancer, which is not indicated by the normal histopathological findings.

**Option C:** This option is incorrect because it implies the presence of a specific type of cell, such as goblet cells, which are not typically found in the gallbladder epithelium.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the gallbladder epithelium can be altered in certain pathological conditions, such as chronic cholecystitis or gallbladder cancer. However, in the absence of any clinical or histopathological evidence of disease, the normal gallbladder epithelium is typically composed of a single layer of columnar epithelial cells.

**Correct Answer: C. Columnar epithelial cells.**