An Insulating Solid Sphere of Radius a Has a Uniform $\rho$

Multiple Choice

An insulating solid sphere of radius a has a uniform volume charge density $\rho$ and total positive charge q.The strength of the electric field inside the sphere at a distance r from the center (r < a) is proportional to

A) a.
B) r.
C) 1/r².
D) 1/r³.
E) 1/a².