Which of Galileo's beliefs was one of the main causes of his conflict with the Catholic Church?

A.
that the Earth was not the center of the universe but rather orbited around the Sun
B.
that the teachings of the Catholic Church were unscientific and incorrect
C.
that the Sun was not the center of the universe but rather orbited around the Earth
D.
that the pope had no authority and no right to be the head of the Catholic Church