A solid metallic rod of length \(L\), cross-sectional area \(A\), and thermal conductivity \(k\) connects a hot thermal reservoir at constant absolute temperature \(T_H\) to a cold thermal reservoir at constant absolute temperature \(T_C\). Heat flows through the rod under steady-state conditions for a time interval \(\Delta t\). Assuming no heat is lost to the surroundings and the rod itself maintains a constant temperature distribution, which of the following expressions correctly represents the total change in entropy of the universe \(\Delta S_{\text{univ}}\)