As air-breathing mammals, whales must once have lived on land and needed hind limbs capable of supporting the mammals' weight. Whales have the bare remnants of a pelvis. If animals have a pelvis, we expect them to have hind limbs. A newly discovered fossilized whale skeleton has very fragile hind limbs that could not have supported the animal' s weight on land. This skeleton had a partial pelvis. If the statements above are true, which one of the following, if also true, would most strongly support the conclusion that the fragile hind limbs are remnants of limbs that land-dwelling whales once had?
A: Scientists are uncertain whether the apparently nonfunctioning limbs of other early mammals derived from once-functioning limbs of their ancestors.
B: Some smaller sea-dwelling mammals, such as modern dolphins, have no visible indications of hind limbs.
C: No skeletons of ancient whales with intact hind limbs capable of supporting the mammals' weight have ever been found.
D: Whale bones older than the fossilized hind limbs confirm that ancient whales had full pelvises.
Choose A, B, C or D as your solution.
D