Which of the following provides the best example of how comparative embryology supports the theory of evolution? a. humans do not lay eggs as birds do, but birds produce yolk sacs instead of embryos, suggesting birds evolved later than humans. / b. humans have a tailbone that is not visible during embryonic development, which suggests that humans evolved to not depend on their tailbone serving a useful purpose. / c. humans do not have gills as fish do, but human embryos have gill slits, suggesting humans and fish share a common evolutionary ancestor. / d. humans have embryonic cells that dev