What does the backbone protect? a. the rib cage c. spinal cord b. cells walls d. notochord

It protects the spinal cord.

In an adult, the vertebral column is made up of 26 bones, from the neck all the way down to the sacrum and coccyx. Children have 33 bones as some of the bones within the sacrum and coccyx fuse together during adolescence. Each bone, or vertebrae, of the spine lines up so the spinal cord can pass through the hollow center. There are small gaps between each vertebrae, called "intervertebral canals," where nerves branch off from the spinal cord and connect the brain to the rest of the body.

The answer is constant.