What is one of kepler's laws of planetary motion?

a. planets move on elliptical orbits with the sun at one focus.
b. gravitational force between two objects decreases as the distance is squared.
c. an object in motion remains in motion.
d. inner planets orbit in the opposite direction of outer ones.

so whats the answer .              

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.