## Core Concept
Giant cell tumors (GCTs) are typically benign but locally aggressive neoplasms that often occur in the epiphyseal ends of long bones, particularly around the knee. They are characterized by the presence of multinucleated giant cells. The most common sites for GCTs are the distal femur, proximal tibia, and distal radius.

## Why the Correct Answer is Right
The correct statement about giant cell tumors is related to their typical presentation and behavior. GCTs usually occur after epiphyseal closure, often presenting in skeletally mature individuals. This characteristic helps in differentiating them from other bone lesions that may occur in younger individuals.

## Why Each Wrong Option is Incorrect
- **Option A:** Without specific details on option A, we cannot directly address its incorrectness. However, common incorrect statements might include claims about the tumor's typical age range, common locations, or histological characteristics.
- **Option B:** Similarly, without specifics, we can't directly refute it. Generally, incorrect statements might involve the tumor's potential for metastasis, its response to certain treatments, or its association with other conditions.
- **Option C:** This option's incorrectness would depend on the claim made. If it suggests GCTs are malignant or have a high metastatic potential, this would be incorrect as they are typically benign but can be locally aggressive.
- **Option D:** If this option suggests a common site or a characteristic feature of GCTs that is not accurate, it would be considered incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **Giant cell tumors** are typically **benign** but can be locally aggressive. They often present in adults after epiphyseal closure, commonly affecting the **distal femur**, **proximal tibia**, and **distal radius**. A classic radiographic feature is a **lytic lesion** that extends to the subchondral bone, often with a "soap bubble" appearance.

**Correct Answer: D.**