During development in the mother's uterus, human embryos have pharyngeal pouches (sometimes called gill slits) that later develop into various glands. Fish also have pharyngeal pouches as embryos, but these develop into gills. The best explanation for why human and fish embryos develop pharyngeal pouches is
A. fish evolved from humans.
B. humans and fish share a common ancestor that had gills.
C. human embryos need gill slits to breathe in the uterus.
D. humans and fish both develop pharyngeal pouches by random chance.
Answer: B
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