**Core Concept**
The patient's symptoms, including a bony expansion in the lower jaw, periosteal bone growth, and paresthesia of the lower lip, suggest a diagnosis related to a benign tumor or cyst affecting the jawbone, specifically the mandible.

**Why the Correct Answer is Right**
The radiographic findings, including periosteal bone growth at the inferior border of the mandible, are characteristic of a tumor that causes a reactive bone response. The paresthesia of the lower lip suggests involvement of the inferior alveolar nerve, which runs through the mandible. The most likely diagnosis is a **cemento-ossifying fibroma** or a **central giant cell granuloma**, but given the periosteal bone growth and paresthesia, a **central giant cell granuloma** is more likely. This tumor type is known to cause a reactive bone response, leading to periosteal bone growth, and can involve the inferior alveolar nerve, causing paresthesia.

**Why Each Wrong Option is Incorrect**

**Option A:** This option is incorrect because a **dentigerous cyst** is a type of odontogenic cyst that typically forms around an unerupted tooth and does not typically cause periosteal bone growth or paresthesia of the lower lip.

**Option B:** This option is incorrect because a **periapical cyst** or **radicular cyst** is a type of odontogenic cyst that forms as a result of pulp necrosis and does not typically cause periosteal bone growth or paresthesia of the lower lip.

**Option C:** This option is incorrect because a **unerupted tooth** can cause a variety of symptoms, including swelling and paresthesia, but periosteal bone growth is not typically associated with an unerupted tooth.

**Clinical Pearl / High-Yield Fact**
When evaluating a patient with a jaw swelling, it's essential to consider the possibility of a benign tumor or cyst, such as a central giant cell granuloma, which can cause periosteal bone growth and paresthesia of the lower lip. These tumors can be challenging to diagnose and may require a combination of radiographic and histopathological evaluation.

**Correct Answer: C. Central giant cell granuloma.**