**Core Concept**
The notochord is a precursor to the spinal cord and is a key structure in the embryological development of the vertebral column. During fetal development, the notochord degenerates and is replaced by the vertebral bodies, but remnants of the notochord persist in the adult human body.

**Why the Correct Answer is Right**
The correct answer is a remnant of the notochord called the nucleus pulposus. The nucleus pulposus is the soft, gelatinous center of the intervertebral disc, which provides cushioning and support to the spine. The notochord's remnants are thought to contribute to the development of the intervertebral discs, with the nucleus pulposus being the remaining portion of the notochord. This structure is essential for maintaining spinal flexibility and shock absorption.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not related to the remnant of the notochord. The vertebral bodies are formed from the somites, not the notochord.
* **Option B:** The spinal cord is a derivative of the neural tube, not the notochord. The notochord is a precursor to the vertebral column, not the central nervous system.
* **Option C:** The annulus fibrosus is a tough, fibrous outer layer of the intervertebral disc, but it is not a remnant of the notochord. The nucleus pulposus is the correct answer.

**Clinical Pearl / High-Yield Fact**
The nucleus pulposus is a remnant of the notochord, and its degeneration can lead to intervertebral disc disease, which is a common cause of lower back pain in adults.

**Correct Answer: C. Nucleus pulposus**