Which of the following statements best describes the relationship between the electric force and the gravitational force acting between two isolated point particles?
(a) Both forces can be either attractive or repulsive and each follows an inverse-square dependence on the separation distance.
(b) The gravitational force is always attractive, whereas the electric force can be either attractive or repulsive; both follow an inverse-square dependence on separation distance.
(c) The gravitational force is always attractive, whereas the electric force can be attractive or repulsive, but the electric force decreases with the cube of the distance between the particles.
(d) Both forces are always attractive and each follows an inverse-square dependence on the separation distance.