Which part of the skeletal system protects the brain?

A. Organism: An organism is the complete living being, composed of multiple organ systems working together. It is not the basic structural or functional unit.

B. Organ: An organ is a collection of tissues that performs a specific function, but it is made up of cells, which are the fundamental units.

C. Tissue: Tissue is a group of similar cells performing a common function. While important, tissues are composed of cells and not the most basic unit.

D. Cell: The cell is the smallest structural and functional unit of life. It carries out essential processes such as metabolism, energy production, and reproduction, forming the foundation of all living organisms.

A. Cardiac muscle: Cardiac muscle is found only in the heart. It contracts involuntarily to pump blood and does not move the skeleton.

B. Smooth muscle: Smooth muscle is located in the walls of internal organs and blood vessels. It controls involuntary movements like peristalsis and vessel constriction, not skeletal movement.

C. Skeletal muscle: Skeletal muscle attaches to bones via tendons and contracts voluntarily to produce movement of the skeleton. It also helps maintain posture and generates heat during activity.

D. Connective tissue: Connective tissue, such as ligaments and tendons, supports and connects structures but does not contract to produce skeletal movement.