Correct Answer: Tailbone

Solution : The correct option is Tailbone.

The tailbone (coccyx) is a vestigial organ present in humans. They may have served a purpose in previous species, but due to changes in the organism's environment or behaviour, they have shrunk in size, and function over time. Human examples include the appendix, and wisdom teeth, which are remains of structures that once had a purpose in evolutionary forebears but are no longer functional or necessary in modern humans.