What are the components primarily included in the axial skeleton?

The axial skeleton comprises the central part of the body and is primarily responsible for protecting the brain, spinal cord, and thoracic organs, as well as providing structural support and stability. The main components of the axial skeleton include the skull, vertebral column (spine), ribs, and sternum.

The skull encases and protects the brain, the vertebral column houses the spinal cord, the ribs protect the thoracic cavity containing the heart and lungs, and the sternum connects the ribs at the front of the body. Together, these components form a crucial structural frame that supports the body and protects vital organs.

In contrast, the other answer choices incorporate elements that belong to the appendicular skeleton, which includes the limbs (arms and legs) and the pelvic girdle. While the spine appears in one of the options, it is not sufficient to qualify that combination as part of the axial skeleton when coupled with elements from the appendicular skeleton.