An ideal parallel-plate capacitor with plate area \(A\) and plate separation \(d\) has initial capacitance \(C_0\). A slab of uniform dielectric material with dielectric constant \(\kappa > 1\) is inserted, completely filling the space between the plates.

Which of the following correctly pairs the new capacitance \(C'\) with the spatial distribution of the electric field magnitude \(E\) inside the dielectric region?