b is ruled out to a "reasonable" person because the Earth is not an inertial reference frame, but is clearly the 'rotating' frame, while the Sun is (approximate

b is ruled out to a "reasonable" person because the Earth is not an inertial reference frame, but is clearly the 'rotating' frame, while the Sun is (approximately) stationary. This is confirmed through the phenomena of stellar parallax and stellar aberration, which are only visible from Earth because of its motion. Even back in the 1573, Thomas Digges and many successors realized they could prove the Earth was in motion using parallax (though had trouble detecting it), and in 1729 James Bradley gave the first proof of heliocentrism using aberration. Both of these observations were taken as proof by the scientific world that the Earth orbits the Sun, and not the other way around.