The diagram below shows illustrations of fossilized forefeet and molar teeth from horses that lived during different time periods. The diagram also shows how the body shape and size of horses has changed over time.

Image courtesy of Jerry Crimson Mann, licensed under CC BY-SA 3.0.

This fossil evidence provides support for the idea that

This fossil evidence provides support for the idea that (a) modern organisms have evolved from earlier species.

Explanation:

Fossil Evidence: Fossils are evidence or clues that have been left behind by living things and are found by archaeologists. They are tools that are helpful for understanding the diverse groups of organisms that have lived in our planet at one time or another.

we define fossil as any preserved evidence of an organism.

i think it is dna, i'm not totally sure but i think it might be.