Two Concentric Conducting Spherical Shells Have Radii R and R

Multiple Choice

Two concentric conducting spherical shells have radii r and R (> r) and charges q and Q, respectively. The electric potential just outside the surface of the shell of smaller radius is proportional to

A) q / r + Q / R.
B) q / R + Q / r.
C) q / r + (q + Q) / (r + R) .
D) q / R + (q + Q) / r.
E) q / r + (q + Q) / R.