Why Was Darwin and Wallace's Theory of Evolution by Natural

Why was Darwin and Wallace's theory of evolution by natural selection revolutionary?

A) It was the first theory to refute the ideas of special creation.
B) It proved that individuals acclimated to their environment over time.
C) It dismissed the idea that species are constant and emphasized the importance of variation and change in populations.
D) It was the first time a biologist had proposed that species changed through time.