Nicholas Copernicus,
He was also the author of the book on the Revolution of Heavenly Bodies. Was a Renaissance-era mathematician and astronomer who formulated a model of the universe that placed the Sun rather than the Earth at the center of the universe, in all likelihood independently of Aristarchus of Samos, who had formulated such a model some eighteen centuries earlier. He use mathematics to prove the earth revolves around the sun, which is why a lot of people know about him, though it isn't the reason that everyone knows him.
So the answer to your question is C. using mathematics to prove the earth revolves around the sun.
:) Hope it helps! I got a A- on the semester test, hope you get a good grade aswell!
EDIT: Realized I'm 2 years late. Sorry!