Concept:The axial skeleton forms the central supporting axis of the human body.
Explanation:The axial skeleton includes the skull and the vertebral column.
It also includes the ribs and the sternum as associated structures.
The skull protects the brain and supports the facial structures.
The vertebral column encloses the spinal cord and supports the trunk.
The limbs and girdles are part of the appendicular skeleton, not the axial skeleton.
The atlas and axis are specific vertebrae within the vertebral column.
The radius and ulna are bones of the forearm, which belong to the appendicular skeleton.
Therefore, the axial skeleton is best described by its two main groups: the skull and the vertebral column.
Answer:A. skull and vertebral column