Evolution Is Sometimes Described as the Change from Preexisting Life-

Evolution is sometimes described as the change from preexisting life- forms to modern- day organisms. What actually changes, in every case of evolution, is the

A) genetic makeup of the species, due to mutations.
B) species' physical appearance.
C) rate of reproduction.
D) energy and nutritional demands of the organism.
E) ability of organisms to respond to external stimuli.