What is included in the appendicular skeleton?

The appendicular skeleton is comprised of the bones that make up the limbs and the structures that attach them to the axial skeleton, which includes the girdles (the pelvic and shoulder girdles) and the limbs themselves (the arms and legs). This part of the skeleton is responsible for facilitating movement and manipulation of the environment, serving as the foundation for upper and lower limb functionality.

In contrast, the other options refer to components of the axial skeleton or specific vertebral sections. The skull and vertebrae make up the axial skeleton, while the ribs and sternum are part of the thoracic cage. Similarly, the cervical and thoracic vertebrae are also components of the axial skeleton. Therefore, focusing on the limbs and girdles distinctly identifies the appendicular skeleton, underscoring why this choice is the most accurate representation of that specific part of human anatomy.