**Core Concept**
Scoliosis is a complex three-dimensional deformity of the spine, characterized by lateral curvature and vertebral rotation. Vertebral rotation is a critical component of scoliosis, as it affects the patient's appearance, respiratory function, and overall quality of life.

**Why the Correct Answer is Right**
Vertebral rotation in scoliosis is typically assessed using the Cobb method, but a more accurate and reliable method is the Nash-Moe classification system. However, for vertebral rotation specifically, the correct answer is the **Vertebral Rotation Index (VRI)**. The VRI is calculated by measuring the angle of vertebral rotation in relation to the sagittal plane, usually using radiographic images. This measurement is essential in evaluating the severity of scoliosis and planning appropriate treatment.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the Cobb angle primarily measures the degree of spinal curvature, not vertebral rotation.
* **Option B:** This option is incorrect because the Nash-Moe classification system is used to assess the severity of scoliosis, not specifically vertebral rotation.
* **Option C:** This option is incorrect because the Lenke classification system is an extension of the Cobb classification, used to subclassify scoliosis, not assess vertebral rotation.

**Clinical Pearl / High-Yield Fact**
The Vertebral Rotation Index (VRI) is a crucial measurement in scoliosis assessment, as it helps predict the risk of progression and guides treatment decisions, such as the need for surgical intervention.

**Correct Answer:** D.