Twelve identical resistors, each having resistance \(R\), are connected together to form the edges of a cube. A steady total current \(I_0\) enters the network at vertex \(A\) and exits at vertex \(B\), which is located at the diametrically opposite body corner of the cube. Which of the following expressions gives the equivalent resistance \(R_{\text{eq}}\) of the network between vertices \(A\) and \(B\)?