**Core Concept**
The question is testing the student's knowledge of dental anatomy and the types of cysts that can occur in the oral cavity. Specifically, it is asking about the characteristics of a cyst that is associated with the root canal of a tooth.

**Why the Correct Answer is Right**
The correct answer is a radicular cyst, which is a type of odontogenic cyst that is associated with the root canal of a tooth. It is caused by the accumulation of bacterial products in the pulp chamber, leading to an inflammatory response and the formation of a cystic cavity. The epithelial lining of the cyst is continuous with the epithelial cells of the periodontal ligament, which makes it a radicular cyst.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the type of cyst that is associated with the root canal of a tooth.

**Option B:** This option is incorrect because it is a type of cyst that is not typically associated with the root canal of a tooth.

**Option D:** This option is incorrect because it is a type of cyst that is not typically associated with the root canal of a tooth.

**Clinical Pearl / High-Yield Fact**
Radicular cysts are the most common type of odontogenic cyst and are often associated with impacted teeth or teeth that have undergone root canal therapy.

**Correct Answer:** C. Radicular cyst.