**Core Concept**
The question is testing the student's knowledge of the anatomy and histology of the developing teeth. Newly erupted teeth are covered by a thin layer of epithelial cells, specifically the junctional epithelium, which forms a seal around the tooth to prevent bacterial invasion.

**Why the Correct Answer is Right**
The junctional epithelium is a specialized type of epithelial tissue that covers the tooth surface, forming a tight seal around the tooth to prevent the entry of bacteria and other foreign substances. This layer is continuous with the oral epithelium and is essential for maintaining oral health. The junctional epithelium is also involved in the formation of the periodontal pocket, which can lead to periodontal disease if not properly maintained.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the cementum is a layer of bone-like tissue that covers the root of the tooth, not the newly erupted teeth.

**Option B:** This option is incorrect because the periodontal ligament is a group of fibers that connect the tooth to the surrounding bone, but it does not cover the newly erupted teeth.

**Clinical Pearl / High-Yield Fact**
The junctional epithelium is a critical structure in maintaining oral health, and its proper formation and function are essential for preventing periodontal disease. Students should remember that the junctional epithelium is a thin layer of epithelial cells that covers the tooth surface, forming a tight seal around the tooth.

**Correct Answer:** C. Junctional epithelium.