Which of the following sets includes only vestigial structures in humans?

The set that includes only vestigial structures in humans is the one that contains the coccyx, the vermiform appendix, and ear muscles.

Each of these structures provides insight into human evolution and their reduced functionality in modern humans. The coccyx, or tailbone, is a remnant of a tail that was once present in our primate ancestors but no longer serves a vital purpose. Similarly, the vermiform appendix is thought to have played a role in the digestive processes of herbivorous ancestors, but in humans, it has a diminished function and is often considered vestigial. The small muscles in the ear, which allow for ear movement in some animals, do not contribute to a significant function in human physiology today.

In contrast, the other choices include structures like nasal bones, wisdom teeth, the gallbladder, body hair, and tonsils. While some of these can be considered reduced in function, they do not classify strictly as vestigial in the same way as the coccyx, appendix, and ear muscles, as they still serve some roles or have evolved to adapt to human physiology in a different manner.