Two solid slabs, 1 and 2, with the same cross-sectional area \(A\) are placed in perfect thermal contact side-by-side between two thermal reservoirs. Slab 1 has thickness \(L_1\) and thermal conductivity \(k_1\), with its outer face maintained at temperature \(T_H\). Slab 2 has thickness \(L_2\) and thermal conductivity \(k_2\), with its outer face maintained at temperature \(T_C\), where \(T_H > T_C\). Assuming energy transfer occurs only along the length of the slabs and the system is in steady state, which of the following expressions represents the rate of heat transfer \(\dfrac{Q}{\Delta t}\) through the two-slab system?