**Core Concept**
Peritubular dentin is a type of dentinal tissue surrounding the dentinal tubules in the tooth. It plays a crucial role in the transmission of stimuli from the dentinal tubules to the pulp. The main difference between peritubular and intertubular dentin lies in their composition, structure, and function.

**Why the Correct Answer is Right**
Peritubular dentin is composed of highly mineralized, dense, and homogeneous tissue that is rich in hydroxyapatite crystals. This characteristic is due to the high concentration of calcium and phosphate ions in the peritubular dentinal fluid. The dense mineralization of peritubular dentin helps to reduce the permeability of the dentin and prevents the flow of dentinal fluid, which is essential for the transmission of stimuli from the dentinal tubules to the pulp. The high mineralization of peritubular dentin also makes it more resistant to caries and other forms of tooth decay.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because peritubular dentin does not contain a higher concentration of collagen fibers compared to intertubular dentin. In fact, peritubular dentin is composed of highly mineralized tissue with a lower concentration of collagen fibers.
* **Option B:** This option is incorrect because peritubular dentin does not have a higher concentration of dentinal tubules compared to intertubular dentin. Instead, peritubular dentin surrounds the dentinal tubules and plays a crucial role in the transmission of stimuli from the tubules to the pulp.

**Clinical Pearl / High-Yield Fact**
The high mineralization of peritubular dentin makes it more resistant to caries and other forms of tooth decay. This characteristic is essential for the long-term health and durability of the tooth.

**Correct Answer: C. Highly mineralized, dense, and homogeneous tissue.**