Two planets are orbiting a star. Planet A is closer to the star than Planet B. Which description explains the expected motion of Planets A and B?
A) The average speed of Planet B is faster than that of Planet A.
B) The average speed of Planet A is equal to that of Planet B.
C) The orbital period of Planet B is shorter than that of Planet A.
D) The orbital period of planet A is shorter than that of Planet B.
