The answer is D. Their jawbone structures are too different.
The asnwer is D.
this is because the traits in all the other options are acquired traits and on this basis, we cannot classify them. Instead, we look for some deeper features like the structure of their bodies. Thus, i conclude that the the answer is D
The observation that best supports the conclusion that dolphins and sharks do not have a recent common ancestor is D, which points to their very different jawbone structures. This anatomical difference implies that they have followed separate evolutionary paths. Other options primarily address behavioral differences or species counts, which are not strong indicators of common ancestry.
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