A parallel plate capacitor, with a slab of dielectric constant k between its plates, has a capacitance C. It is charged to a potential V. Now the dielectric slab is first brought out of the capacitor and is then introduced again. The work done in this process will be
A. `(k-1)(CV^2)/(2)`
B. `(CV^2(k-1))/(k)`
C. `(k-1)CV^2`
D. 0
