Concept:Homologous structures share a common evolutionary origin but may perform different functions.Explanation:Structures are homologous when they are inherited from a common ancestor but have been modified for different roles.For example, the forelimbs of humans, bats, and whales all have similar bone arrangements yet are used for different functions.Such structures are known as homologous structures.Analogous structures, by contrast, are similar in function but not in origin.Answer:A. homologous structures