The correct option is A Vertebrae
The spine (also called as the vertebral column or spinal column) is composed of a series of bones called as vertebrae stacked one upon another. The vertebral column is the scientific, anatomical word for the spine or backbone. It is a column of vertebrae in the back part of the torso (upper body). There is a canal that runs through the length of the backbone. Inside this canal is the spinal cord. Animals, including humans, that have a vertebral column are called vertebrates and animals that don't have one are called as invertebrates.