Which part of the skeletal system includes the skull, spinal column, sternum, and ribs?

The correct answer is the axial skeleton, which includes the skull, spinal column, sternum, and ribs. This part of the skeletal system serves a critical role in protecting the vital organs and providing support for the body’s structure. The skull encases the brain and protects it from injury; the vertebrae in the spinal column protect the spinal cord and provide support for the upper body; the sternum and ribs form the rib cage, which safeguards the heart and lungs.

In contrast, the appendicular skeleton encompasses the limbs and the girdles that connect them to the axial skeleton, such as the arms, legs, pelvis, and shoulder bones. The term "peripheral skeleton" is not standard in anatomy, as it might refer to parts that are further away from the center of the body but is not used in established contexts. The articulated skeleton refers to bones that are connected and arranged as they would be in a living organism, typically used in discussions about joint movement or structure but does not specifically denote the components listed in the question.