15. Over the last century, paleontologists have used small differences between fossil specimens to classify triceratops into sixteen species. This classification is unjustified, however, since the specimens used to distinguish eleven of the species come from animals that lived in the same area at the same time.
Which of the following, if true, would enable the conclusion of the argument to be properly drawn?
(A) Not every species that lived in a given area is preserved as a fossil.
(B) At least one individual of every true species of triceratops has been discovered as a fossil specimen.
(C) No geographical area ever supports more than three similar species at the same time.
(D) In many species, individuals display quite marked variation.（C）
(E) Differences between fossil specimens of triceratops that came from the same area are no less distinctive than differences between specimens that came from different areas.
