## Core Concept
The question tests knowledge of the spinal ligaments and their role in limiting spinal movements. The vertebral column has several ligaments that provide stability and restrict excessive movements. Understanding the specific ligaments and their functions is crucial for clinical diagnosis and management of spinal injuries.

## Why the Correct Answer is Right
The **anterior longitudinal ligament (ALL)** is a strong ligament that runs along the anterior aspect of the vertebral bodies, from the base of the skull to the sacrum. It is the primary ligament responsible for limiting **extension** of the vertebral column. During extension, the ALL becomes taut, thereby restricting further movement. This ligament plays a critical role in maintaining spinal stability, especially in preventing excessive extension injuries.

## Why Each Wrong Option is Incorrect
* **Option A:** The **supraspinous ligament** connects the tips of the spinous processes of adjacent vertebrae and is involved in limiting flexion, not extension.
* **Option B:** The **posterior longitudinal ligament (PLL)** runs within the spinal canal, along the posterior aspect of the vertebral bodies, and is more involved in limiting **flexion** of the vertebral column.
* **Option D:** The **interspinous ligaments** are located between the spinous processes and provide additional stability but are not the primary ligaments limiting extension.

## Clinical Pearl / High-Yield Fact
A key clinical correlation is that the **anterior longitudinal ligament** is often injured in **flexion-compression fractures** or in severe **whiplash injuries**, which can lead to instability of the cervical spine. Clinicians should be aware of the ligamentous injuries when evaluating spinal trauma.

## Correct Answer Line
**Correct Answer: C. Anterior longitudinal ligament.**