Answer:
The skull protects the brain from any direct damage and the vertebrae helps keep the nerves in the spine in place and protected from damage. So the central nervous system is protected by the vertebrae and the skull.
The human body is organized at different levels, starting with the cell. Cells are organized into tissues, and tissues form organs. Organs are organized into organ systems such as the skeletal and muscular systems.
I think it's D. all of the above.