Two thin, concentric, conducting spherical shells have radii \(R\) and \(2R\). The inner shell carries a net charge \(+Q\), and the outer shell carries a net charge \(-2Q\). The electric potential is defined to be zero at an infinite distance from the shells (\(V = 0\) as \(r \rightarrow \infty\)). Which of the following graphs best represents the electric potential \(V\) as a function of distance \(r\) from the common center of the shells?