Final answer:
The subject of this question is Biology. Humans do not have vestigial organs. The pharyngeal arches and gill slits in human embryos do not develop into functional gills. Therefore, the correct answer is c) Vestigial organs.
Step-by-step explanation:
The subject of this question is Biology. The question asks which option, a) Tails, b) Appendices, c) Vestigial organs, or d) Gills, humans do not have. According to the provided information, the correct answer is c) Vestigial organs. Vestigial structures are organs or structures that have reduced in size and no longer serve a function. Examples include the human tailbone (coccyx) and the appendix. While the human embryo exhibits pharyngeal arches and gill slits (incorrectly referred to as gills), humans do not have functional gills. Therefore, option d) Gills is not correct.