What Was Revolutionary About Copernicus's Theory in on the Revolution

What was revolutionary about Copernicus's theory in On the Revolution of the Heavenly Bodies ?

A) He argued that there were other planets outside our solar system.
B) He argued that it was possible there was life on other planets.
C) He argued that the Earth was part of a larger system orbiting the sun.
D) He argued that gravity held all the planets in line with the sun.
E) He argued that God had not created the universe but that it just existed.