A dielectric slab of thickness \[d\] is inserted in a parallel plate capacitor whose negative plate is at \[x=0\] and positive plate is at \[x=3d\]. The slab is equidistant from the plates. The capacitor is given some charge. As one goes from 0 to \[3d\] [IIT-JEE 1998]

• A.                    The magnitude of the electric field remains the same
• B.                    The direction of the electric field remains the same
• C.                    The electric potential increases continuously
• D.                    The electric potential increases at first, then decreases and again increases