A multi-loop circuit consists of two ideal batteries with electromotive forces \(\varepsilon_1\) and \(\varepsilon_2\), and three resistors with resistances \(R_1\), \(R_2\), and \(R_3\), as shown in the schematic diagram. The currents in the three branches are defined as \(I_1\), \(I_2\), and \(I_3\), with directions indicated by the arrows. Which of the following equations correctly expresses Kirchhoff's loop rule for the outer loop when traversed in a clockwise direction?