Which statement explains why animals possess homologous structures?

The presence of homologous structures in animals is primarily explained by the fact that these structures evolved from a common ancestor. Homologous structures are anatomical features that are similar in different species due to shared ancestry, even though they may serve different functions in the current organisms. A classic example is the forelimbs of mammals, birds, and reptiles, which have similar underlying bone structures but have adapted to different environments and ways of life.

This shared origin indicates that these diverse forms can trace back to a common evolutionary pathway. As species adapt to various habitats, their homologous structures may diverge in function and appearance, but their similarities highlight evolutionary relationships and the process of descent with modification. Overall, this concept reinforces the idea of evolution and the interconnectedness of life forms.