D
A recently discovered fossil, which is believed by some to come from Archaeoraptor liaoningensis, a species of dinosaur, can serve as evidence that birds evolved from dinosaurs only if the entire fossil is from a single animal. However, the fossil is a composite of bones collected from various parts of the discovery site, so it does not provide evidence that birds evolved from dinosaurs. The conclusion drawn in the argument follows logically if which one of the following is assumed?
A: If the entire fossil is from a single animal, then it is a well-preserved specimen.
B: The only paleontologists who believe that the entire fossil is from a single animal are those who were already convinced that birds evolved from dinosaurs.
C: The fossil was stolen from the discovery site and sold by someone who cared much more about personal profit than about the accuracy of the fossil record.
D: If the fossil is a composite, then it has pieces of more than one animal.