Which part of the skeletal system includes the arms, legs, pelvis, and shoulder girdle?

The appendicular skeleton is the correct choice because it specifically comprises the bones of the limbs and the supporting structures that connect them to the axial skeleton. This includes the arms (humerus, radius, ulna, etc.), legs (femur, tibia, fibula, etc.), pelvis (hip bones), and the shoulder girdle (scapula and clavicle).

In contrast, the axial skeleton consists of the bones that form the central axis of the body, including the skull, vertebral column, and rib cage. The cranial skeleton pertains solely to the bones that house and protect the brain, while the facial skeleton comprises the bones that form the face. Therefore, the appendicular skeleton is distinct in its role and composition, primarily focusing on the limbs and their connections.