An uncharged parallel-plate capacitor of capacitance \(C\) is connected in series with a resistor of resistance \(R\) and an ideal battery of potential difference \(\mathcal{E}\). When the switch is closed, the potential difference \(V_C\) across the capacitor begins to increase, but the rate of potential change \(\dfrac{dV_C}{dt}\) continuously decreases over time. Which of the following best explains why this rate of potential change decreases as the capacitor charges?