Homologous structures can be best be described as structures that ...

are so similar that they imply a common ancestor

have the same structures and functions

have the same structures

had a function in an ancestor but don't have that function today

Homologous structures can be best be described as structures that are are so similar that they imply a common ancestor.

Answer: Option A

Explanation:

In evolution a number of organisms have lost some of their structures and a number of organisms have gained some of their structures for their survival. According to Darwin, the most fittest organism has survived.

For exhibiting this many organisms have attained several modifications. So when we look into homologous structures in 2 different species we can thereby relate and tell that they are from a common ancestor.

Homologous structures can be best described as structures that are so similar that they imply a common ancestor.

Homologous structures are structures that can be found in different species and are similar in structure but may not necessarily have similar function. The presence of these similar structures indicates that the species evolve from a common ancestor. Examples of homologous structures are the forelimbs of bats and humans which have different functions but the same basic skeletal structure. This suggests that bats and humans share a common ancestor.