**Core Concept**
The "soap bubble" appearance on an X-ray of the wrist is a radiological sign associated with a specific bone disorder. This sign is characterized by multiple, well-defined lucencies (dark areas) within the epiphyseal region of the bones, resembling the appearance of soap bubbles.

**Why the Correct Answer is Right**
The soap bubble appearance is a classic radiological feature of **Fibrous Dysplasia**, a benign bone disorder where normal bone tissue is replaced by fibrous connective tissue. This replacement leads to the characteristic lucencies seen on X-ray, which are a result of the fibrous tissue's lower density compared to normal bone. Fibrous dysplasia can occur in any bone but is most commonly seen in the long bones of the limbs, including the wrist.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the soap bubble appearance on X-ray.
* **Option B:** This option is incorrect because **Osteogenesis Imperfecta** is characterized by brittle bones, not the soap bubble appearance.
* **Option C:** This option is incorrect because **Paget's Disease** is a condition that affects bone remodeling, resulting in enlarged and deformed bones, not the soap bubble appearance.

**Clinical Pearl / High-Yield Fact**
Fibrous dysplasia can lead to bone deformities and fractures due to the weakened bone structure. It is essential to consider this condition in the differential diagnosis of patients presenting with soap bubble appearance on X-ray.

**Correct Answer: C. Fibrous Dysplasia**