**Core Concept**
The presence of elevated protein levels in cystic fluid is a characteristic feature that helps in distinguishing between various types of cysts. This is particularly relevant in the context of odontogenic cysts, where the protein content can aid in diagnosis and management.

**Why the Correct Answer is Right**
Osteogenic Keratocyst (OKC), also known as Keratocystic Odontogenic Tumor (KCOT), is a type of odontogenic cyst characterized by its aggressive behavior and potential for recurrence. Unlike other odontogenic cysts, OKC typically has a low protein content in its cystic fluid, usually less than 4-5 grams/100ml. This is because OKC is primarily composed of keratinized epithelium, which does not produce significant amounts of protein. In contrast, other cysts like radicular cysts and dentigerous cysts have higher protein levels due to the presence of inflammatory cells and fluid.

**Why Each Wrong Option is Incorrect**
* **Option A:** Dentigerous cysts, on the other hand, are known to have high protein levels in their cystic fluid, typically exceeding 4-5 grams/100ml. This is due to the presence of fluid and inflammatory cells within the cyst.
* **Option C:** Radicular cysts, also known as periapical cysts, usually have high protein levels in their cystic fluid, often above 4-5 grams/100ml. This is a result of the inflammatory response and fluid accumulation within the cyst.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the protein content in cystic fluid can be used as a diagnostic aid, especially in differentiating between OKC and other odontogenic cysts. A low protein level in the cystic fluid may suggest OKC, while high protein levels may indicate other types of cysts.

**✓ Correct Answer: B. OKC.**