A rectangular dielectric slab of dielectric constant \(\kappa > 1\) is partially inserted a distance \(x\) into a parallel-plate capacitor. The capacitor is connected to a battery that maintains a constant potential difference \(V_0\) across the plates, and the slab is free to slide horizontally without friction. Which of the following claims correctly describes the direction of the electrostatic force exerted on the slab by the capacitor and provides the correct justification?