Which part of the skeleton includes the bones of the skull, thorax, and vertebrae?

The axial skeleton is the correct choice as it refers to the central core of the human skeleton, which includes the skull, vertebral column (or spine), and rib cage (thorax). This part of the skeleton is primarily responsible for protecting the vital organs, providing structural support, and facilitating the body's posture and movement. The skull encases and protects the brain, while the vertebrae encircle the spinal cord and the rib cage shields the heart and lungs.

In contrast, the appendicular skeleton comprises the limbs and the girdles that attach them to the axial skeleton. The cranial skeleton specifically refers to the bones that make up the skull, but it does not include the vertebrae or thoracic bones. The term "peripheral skeleton" is not standard in anatomical terminology, so it does not accurately represent any recognized part of the skeleton. Hence, the axial skeleton is the comprehensive term that encapsulates the bones in question.