A dielectric of relative permittivity k completely fills the space between the plates of a parallel-plate capacitor. When the surface charge density on the plates is σ, the polarization of the dielectric is
(A) σ (k – \(\cfrac 1k\))
(B) \(\cfrac σk\)
(C) σ (1 – \(\cfrac 1k\))
(D) σ (k – 1)
