**Core Concept**
The clinical presentation of a bony expansile swelling with mild paresthesia and a multi-locular radiolucency on an orthopantomogram (OPG) suggests a jaw lesion. The key to diagnosis lies in the combination of clinical, radiological, and aspirate findings.

**Why the Correct Answer is Right**
A dirty white aspirate with a low protein estimation is characteristic of a **Stafne bone cavity** or more likely, given the clinical context, a **simple bone cyst** or **Stafne bone cavity** is less likely given the expansile nature and the specific protein content of the aspirate. However, the description best fits a **simple bone cyst**, which often presents with similar radiographic and aspirate findings.

**Why Each Wrong Option is Incorrect**
**Option A:** Might suggest a different type of jaw lesion, but without the specific details, it's hard to pinpoint why it's incorrect based on the aspirate and radiographic findings alone.
**Option B:** Could be considered if the aspirate had suggested a different type of lesion, such as an odontogenic cyst or tumor, but the description provided doesn't align well with these.
**Option C:** If this option suggested a **simple bone cyst**, it would be correct based on the provided description, but without the option details, we can't confirm this match.
**Option D:** Similar to Option A and B, without specifics, it's challenging to determine why it's incorrect, but it doesn't match the description given for the correct answer.

**Clinical Pearl / High-Yield Fact**
The presence of a **dirty white aspirate** with low protein content is a critical diagnostic clue. This, combined with the radiographic appearance of a multi-locular radiolucency without root resorption, points towards a **simple bone cyst**. Remember, the key to diagnosing jaw lesions often lies in the combination of clinical presentation, radiographic findings, and aspirate characteristics.

**Correct Answer:** D. Simple Bone Cyst.