The correct answer is option 1, that is, there is an evolutionary link between the classes.
The study of one kind of proof of evolution is known as embryology, that is, the study of embryos. An embryo refers to an unborn young in its initial stages. Embryos of various distinct types of animals, that is, mammals, reptiles, birds, fishes, etc. seems very identical and it usually becomes tough to differentiate them apart.
Various traits of one kind of animal are observed in the embryo of another kind of animal. This illustrates that the animals are identical and that they are developed identically, signifying that they are associated, have common descendants and that they began the similar, slowly developing distinct traits, however, the fundamental plan for the beginning of the creature remains similar.
