Which part of the skeleton does the appendicular skeleton include?

The appendicular skeleton consists of the bones that form the limbs and the limb girdles that attach them to the axial skeleton. This includes the arms and shoulder girdle (scapula and clavicle), as well as the legs and pelvic girdle (hip bones). This part of the skeleton is responsible for facilitating movement and providing attachment points for muscles involved in locomotion and manipulation of objects.

The other options refer to parts of the skeleton that do not fall under the category of the appendicular skeleton. The skull and backbone are components of the axial skeleton, which also includes the ribs and sternum. The vertebrae are part of the spinal column, which is also axial, and while the pelvis is often associated with the legs, it belongs to the appendicular skeleton as part of the pelvic girdle. Thus, the distinction of appendicular bones lies specifically in the functionality and structure of the limbs and their attachment points.