If $R_s$ and $R_p$ are the equivalent resistances of $n$ resistors, each of value $R$, in series and parallel combinations respectively, then the value of $(R_s - R_p)$ is : (A) $\left(\frac{n^2 - 1}{n^2}\right)R$ (B) $\left(\frac{n^2 + 1}{n^2 - 1}\right)R$ (C) $\left(\frac{n^2 - 1}{n}\right)R$ (D) $\frac{(n^2 + 1)R}{n^2}$