The image shows embryos of three vertebrate classes. Illustration from left: fish embryo, amphibian embryo, and reptile embryo. All embryos look similar but for the thoracic and the caudal region of the snake, which is more protrusive than fish and amphibian, with amphibian being least protrusive. Which conclusions can be made about the animals of each class based on the structural similarities of the embryos? There is an evolutionary link among the classes. The adults of each class may share structural similarities. Reptiles must have given rise to fish and amphibians. Animals of each class have analogous structures.