What constitutes the appendicular skeleton in the human body?

The appendicular skeleton consists of the bones that make up the limbs and their attachments to the axial skeleton. This includes the bones of both the upper extremities, such as the arms, shoulders, and hands, as well as the lower extremities, which encompass the legs, hips, and feet. The primary function of the appendicular skeleton is to facilitate movement and support the body's weight during locomotion and various activities. This skeletal structure is critical for a wide range of motions, from reaching and grasping with the arms to walking and running with the legs.

Other choices do not provide a complete representation of the appendicular skeleton. Focusing solely on the upper or lower extremities misses important components, while including the skull and vertebrae pertains to the axial skeleton, which serves different functions related to protection and support of the central nervous system. Thus, the correct answer encompasses both the upper and lower extremities of the human body.