Answer:
The correct answer would be "Birds and reptiles evolved from a common ancestor".
Homologous organs or structures refer to the set of organs or structure which are similar in internal structure but vary in their functions. The similar structure often demonstrates the common origin or ancestors.
Different organisms adapt to perform different functions as an adaptation against the varying environment.
For example, front limbs of reptiles and birds are similar in structure as they are made up of a similar set of bones, however, they differ in their functions due to adaptations against the varying environment.