Kepler modified copernicus's model of the universe by proposing that the a. planets follow a circular orbit around the sun. b. paths of the planets follow an elliptical orbit around the sun. c. planets have their own orbits around themselves as they orbit the sun. d. planets follow an elliptical orbit every leap year.

B. Paths of the planets follow an elliptical orbit around the sun.

Explanation:

As per Copernicus model of the universe he explained that all planets revolves around the sun in circular orbit with sun at the center of the of the path.

Now as per his theory Radius of orbit of all planets are different and the centripetal force provided by the sun for the circular path of the planets

Now as per his theory all planets must have to move with uniform speed around the sun but this was not true as we can see that the speed of all planets are different at different positions.

So here in order to correct his theory Kepler gives his law of planetary motion that all planets revolves around the sun in elliptical orbit with position of sun as one of its focus.

This path verify all the experimental results of planetary motion and hence correct answer will be

B. Paths of the planets follow an elliptical orbit around the sun.