Similar structures are present in the embryos of fish, chickens, and rabbits. In fish, these structures develop into gills, but in chickens and rabbits, they either disappear or develop into other body parts later in embryonic development. Which of the statements below best explains the presence of these structures in the embryos of all three species?

The embryos of the three species are similar in size.
Breathing structures are similar among the young of the three species.
The three species have a common ancestor with these embryonic structures.
The reproductive mechanisms are similar among the adults of the three species.