**Core Concept**
The question is testing the knowledge of the histological structure of cementum, a bone-like substance covering the root of teeth. Cementum is composed of fibers, cells, and a mineralized matrix. The calcification of cementum fibers is a unique characteristic that distinguishes it from other connective tissues.

**Why the Correct Answer is Right**
The correct answer refers to the presence of **Sharpey's fibers** in cementum. Sharpey's fibers are collagen fibers that have become embedded in the cementum matrix during its formation. These fibers are completely calcified, meaning they are mineralized and integrated into the cementum structure. This unique feature of Sharpey's fibers is essential for the attachment of periodontal ligaments to the cementum.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely referring to collagen fibers, which are present in various connective tissues but are not specifically calcified in cementum.
**Option B:** This option may be referring to cementocytes, the cells found in cementum, but they are not fibers and are not calcified.
**Option C:** This option is likely incorrect as it is not a specific type of fiber found in cementum.

**Clinical Pearl / High-Yield Fact**
To remember the key features of cementum, recall the phrase "SCC" which stands for **Sharpey's fibers**, **Cells** (cementocytes), and **Calcification** (the mineralized matrix). This mnemonic will help you associate the unique characteristics of cementum with its histological structure.

**Correct Answer:** C. Sharpey's fibers.