Final answer:
Homologous structures are evidence of common ancestry and are an aspect of comparative anatomy that supports the theory of evolution. Option A).
Step-by-step explanation:
Having homologous structures is an example of evidence for evolution provided by comparative anatomy. These structures, such as the bones in the limbs of humans and whales, suggest a common evolutionary ancestor. The presence of homologous structures means that, despite various forms and functions in different species, these features share a similar overall construction due to heredity from an ancestor. Comparative embryology, molecular genetics, and the fossil record are other types of evidence for evolution. However, it is the anatomical similarities that are directly observed in homologous structures that serve as a compelling testament to common ancestry and the diversification of species over time.