Final answer:
The average length of an adult spinal cord is 16-18 inches. It is protected by the vertebral column, which consists of 26 bones divided into different regions: cervical, thoracic, lumbar, and sacral.
Step-by-step explanation:
The average length of an adult spinal cord is 16-18 inches (A). The spinal cord is a long, thin bundle of nervous tissue that extends from the brain stem down the center of the back. It is protected by the vertebral column, which consists of 26 bones divided into different regions: cervical, thoracic, lumbar, and sacral.