Answer:
C. Sacrum
Step-by-step explanation:
The axial skeleton makes up the bones along the central system of the body, while the appendicular skeleton comprises the bones along the appendages of the body (in other words, arms, feet, legs, etc).
The clavicle is the collarbone; scapula is shoulder blade bone; and ilium is the hip bone. Of the four choices, only the sacrum, which is at the base of the spinal cord, is located along the central axis of the body and is thus part of the axial skeleton.
C is the answer.