Answer the following question given this paragraph: 

Some unexpected traits can appear in animal embryos. For example, human embryos have gill slits just like fish! In fish they develop into gills, but in humans they disappear before birth. The presence of the gill slits suggests that a long time ago humans and fish shared a common ancestor.


Q: What does the presence of gill slits suggest about humans and fish?

 Choices:

- Shared History

- Common Cells

- Same evolutionary chain

- common ancestor

A:
common ancestor
