Scientists have discovered a fossil skeleton of a whale-like creature that lived in the early Eocene epoch. The skeleton shows an organism with large fore and hind limbs with distinct toes. Fossil skeletons of closely related species from later periods show organisms lacking hind limbs. Which conclusion does this observation best support? A. Ancestors of whales may once have been able to walk.

B. Ancestors of whales had fewer bones than modern whales.

C. Whales and their ancestors have always been ocean dwellers.

D. Whales and their ancestors have always been the largest living ​