## Core Concept
Ollier's disease is a rare congenital disorder characterized by the presence of multiple **enchondromas**, which are benign cartilage tumors within the bones. This condition leads to bone deformities and an increased risk of malignant transformation. It is a type of **skeletal dysplasia**.

## Why the Correct Answer is Right
Ollier's disease is also known as **Multiple Enchondromatosis**. This name directly reflects the pathological hallmark of the condition, which is the presence of multiple enchondromas. These enchondromas are benign tumors that arise from cartilage and are located within the medullary bone. The condition affects bone development and growth, leading to various skeletal abnormalities.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is blank and does not provide any relevant information.
- **Option B:** This option is also blank and does not offer any useful detail.
- **Option C:** Similarly, this option is blank and lacks relevant content.
- **Option D:** This option is correct and identified as such in the question stem.

## Clinical Pearl / High-Yield Fact
A key clinical pearl to remember is that patients with Ollier's disease have an increased risk of **malignant transformation** of enchondromas into **chondrosarcomas**. This risk necessitates long-term follow-up and monitoring for any changes in the bones that could indicate cancer development.

## Correct Answer Line
**Correct Answer: D. Multiple Enchondromatosis**.