## **Core Concept**
The pisiform bone, one of the eight carpal bones in the wrist, has a unique characteristic regarding its ossification. Unlike many other bones, the pisiform bone is known for its late ossification.

## **Why the Correct Answer is Right**
The ossification center of the pisiform bone appears relatively late compared to other carpal bones. Typically, the ossification centers for most carpal bones appear between 1 to 5 years of age. However, the pisiform bone's ossification center appears much later, around **12-15 years of age**. This delay is a notable characteristic of the pisiform bone.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option suggests an age that is too early for the appearance of the pisiform bone's ossification center, as most carpal bones start ossifying before this age.
- **Option B:** Similarly, this option is also too early for the specific case of the pisiform bone.
- **Option C:** This option might seem plausible but is still not accurate for the pisiform bone's ossification timeline.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the pisiform bone is the last of the carpal bones to ossify, with its center appearing around **12-15 years of age**. This fact can be crucial for radiologists and orthopedicians when assessing wrist development, especially in pediatric patients.

## **Correct Answer:** D. 12-15 years.