During their early stages of development, the embryos of reptiles, birds, and mammals look very similar. The embryos of reptiles, birds, and mammals also have many of the same structures and develop in similar patterns. This suggests that reptiles, birds, and mammals... *

share a common ancestor

Explanation:

The similarity in their embryos and embryonic development suggests that reptiles, birds, and mammals share the same ancestor.

Similarity in the structure and development of embryo is one of the evidences that is been used by scientists to support the theory of evolution of species. According to the theory of organic evolution, all organisms are on earth as a result of descent with modifications from common ancestors.

Reptiles, birds, and mammals are all vertebrates. They share some basic characteristics and are thought to have shared a common ancestor before each group took different adaptive channels leading to their  differences as they currently exist.

i think the answer is g1

hope i

-lavira: )