He arm or forelimb of humans, horses, goats, and mice all exhibit the same three bone structures: humerus, ulna, and radius. which statement best explains this common skeletal structure? a) the limb bones are similar across these species because they share a common ancestor. b) the limb bones are the same across these species because all of them move in a similar way. c) the limbs are similar because of the recurring patterns of genetic mutation that are common in the animal kingdom. d) the limbs are structurally similar due to convergent evolution--different organisms evolving to become structurally similar.