Similarity of bone structure in the forelimbs of many vertebrates...

Similarity of bone structure in the forelimbs of many vertebrates, such as whales, bats, cheetahs, and humans, is a classic example of homologous organs.

These organs share a common anatomical plan and embryonic origin but have been modified to perform different functions in different animals, such as swimming, flying, running, and grasping.

This phenomenon indicates divergent evolution, where a common ancestral structure has evolved in different directions to adapt to various environmental needs.

Answer: homologous organs