Far away from any of the resonance frequencies of a medium, the real part of the dielectrie permittivity is (a) always independent of frequency (c) monotonicall

Far away from any of the resonance frequencies of a medium, the real part of the dielectrie permittivity is (a) Always independent of frequency (c) Monotonically increasing with frequency (d) A non-monotonic fiunction of frequency (b) Monotonically decreasing with frequency