Final answer:
The thoracic spine has the greatest range of motion for rotation in the vertebral column, limited in flexion, extension, and lateral flexion by its structure.
Step-by-step explanation:
The thoracic spine is known for its limitation in certain movements due to the structure of the thoracic vertebrae and the attached thoracic cage. Unlike the cervical and lumbar regions, which allow for more flexion, extension, and lateral flexion, the thoracic region has down-projecting and overlapping spinous processes that limit these movements. However, these anatomical features, along with the orientation of the superior and inferior articular processes, make the thoracic spine the region with the greatest range of rotation within the vertebral column. Thus, the answer to the question is b. thoracic, as it has the greatest range of motion for rotation compared to the cervical, lumbar, and sacral regions.