Answer:
I believe: C."Because the embryos all began to develop similarly, this could suggest a common ancestor." would be the best fitting of the current answer choices.
Explanation:
Process of elimination.
We know that organisms of the same species would all look essentially the same, and we know from the second image that they are nowhere near the same species.
Fish Embryos don't really have much to do with this overall, with the majority of the Embryos being from Mammals.
That leaves option C.
(I also somewhat remember this question from back when I was in AP Biology)