A parallel-plate capacitor with plate area \(A\) and air in the gap has its negative plate fixed at position \(x = 0\) and grounded (\(V = 0\)), and its positive plate initially located at position \(x = d\). The capacitor is charged to a magnitude of charge \(Q_0\) and then electrically isolated from the charging source. The positive plate is then slowly pulled to a new position \(x = 2d\) while the charge on each plate remains constant. Which of the following best describes the graph of the electric potential \(V\) as a function of position \(x\) between the plates for the new configuration compared to the initial configuration?