Observationally, the Biggest Difference Between Quasars and Other Active Galaxies

Observationally, the biggest difference between quasars and other active galaxies such as Seyfert and radio galaxies appears to be that

A) quasars appear to be located inside elliptical galaxies, whereas Seyfert and radio galaxies are spirals.
B) Seyfert and radio galaxies do not have the bright, starlike nuclei of quasars.
C) the brightness of Seyfert and radio galaxies does not vary with time.
D) Seyfert and radio galaxies are less powerful energy emitters than quasars.