Two objects each have total charge +Q and the same outer radius R. Object I is a solid insulating sphere of uniform volume charge density. Object II is a thin conducting spherical shell. Which of the following correctly compares the radial dependence of the electric-field magnitude E for the two objects?
a) For r<R, the electric field is zero for both objects because a Gaussian surface encloses no net charge; for r>R, the electric field of the conducting shell exceeds that of the solid sphere at all distances.
b) For r<R, E for object I is constant and non-zero while E for object II is zero; for r>R, the two graphs coincide.
c) For r<R, E for object I increases linearly with r while E for object II is zero; for r>R, the two graphs coincide.
d) For r<R, E for object I increases linearly with r while E for object II is zero; for r>R, E for object II exceeds that of object I because its charge lies on the surface.