The correct answer is (d) birds have evolved from reptiles.
Explanation:
Feathers are homologous structures in both birds and some dinosaurs, meaning they share a common evolutionary ancestry. Since birds have feathers and the ability to fly, while some non-flying dinosaurs also had feathers, it indicates that birds evolved from a lineage of dinosaurs.
Why other options are incorrect:
(a) reptiles have evolved from birds:
This is the reverse of the evolutionary relationship. Fossil evidence, like Archaeopteryx, shows a transitional form between reptiles and birds, suggesting birds evolved from reptiles.
(b) there is no evolutionary connection between reptiles and birds:
This is incorrect. Paleontological evidence, particularly the presence of feathered dinosaurs and the transitional fossil Archaeopteryx, demonstrates a clear evolutionary connection between reptiles and birds.
(c) feathers are homologous structures in both the organisms:
While this statement is technically true, it doesn’t fully explain the evolutionary relationship between birds and reptiles. Homology simply means feathers share a common ancestral origin in both groups, but it doesn’t directly explain the evolutionary progression from non-flying dinosaurs to flying birds.