In the circuit loop shown, an ideal battery of electromotive force \(\varepsilon\) is connected to two resistors, \(R_1\) and \(R_2\). A student claims that traversing the closed loop from point \(A\) back to point \(A\) results in a net electric potential change of zero (\(\sum \Delta V = 0\)). Which of the following correctly identifies the fundamental physical principle that justifies this claim and provides the correct physical reasoning?