Which of the following is the vestigial bony part of the human skeleton?

The coccyx is the tailbone at the bottom of your spine. It is called vestigial because it is a leftover from when human ancestors had tails.

Vestigial means a body part that no longer serves its original purpose. The coccyx has no important function in modern humans, though it provides minor muscle attachment points.

All other options are functional parts of the skeleton. Only the coccyx is a vestigial bone that humans inherited from tailed ancestors.